@article{chizhik_acceleration_2025,

title = {Acceleration of domain wall motion in metallic cylindrical multilayer},

author = {Alexander Chizhik and David Robles-Cuenca and Ricardo López and J. P. Andrés and J. A. González and Valentina Zhukova and Juan Mari Blanco and Arcady Zhukov},

url = {https://www.sciencedirect.com/science/article/pii/S0924424725010659},

doi = {10.1016/j.sna.2025.117259},

issn = {0924-4247},

year  = {2025},

date = {2025-11-01},

urldate = {2025-11-07},

journal = {Sensors and Actuators A: Physical},

pages = {117259},

abstract = {In the context of searching for active elements of magnetic sensors, a new method for local control of domain wall motion in magnetic microwires was proposed. We have classified the microwire - cobalt coating system as a cylindrical multilayer. The coating of a microwire with a thin layer of cobalt in the form of a tube or half-tube leads to local acceleration of domain wall motion when it passes under the cobalt coating. The difference in the velocity in the coated and uncoated areas can reach 3-5 times depending on the type of coating. The study of the domain wall velocity was carried out using the Sixtus-Tonks method. A series of explanatory fluxmetric and magneto-optical experiments were also carried out. The main mechanism of the effect of the cobalt coating is associated with the distribution of stray fields induced by the coating. The axially directed demagnetization field in the case of a tube-type coating, or a combination of axial and perpendicular demagnetization fields, as in the case of a half-tube, make the main contribution to the local control of domain wall mobility.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{fadel_carbonization_2025,

title = {Carbonization driven magnetic domain evolution in Ni@C Nanocomposites: Impact on magnetic anisotropy and heating efficiency},

author = {M. Fadel and P. Álvarez-Alonso and M. Rivas and A. Adawy and J. L. Sánchez Llamazares and Ricardo López and Shah Qasim Jan and Rajeswari Roy Chowdhury and Darío A. Arena and Hariharan Srikanth and Jesús A. Blanco and F. Suarez-García and Pedro Gorria},

url = {https://www.sciencedirect.com/science/article/pii/S0264127525012584},

doi = {10.1016/j.matdes.2025.114838},

issn = {0264-1275},

year  = {2025},

date = {2025-11-01},

urldate = {2025-11-12},

journal = {Materials & Design},

volume = {259},

pages = {114838},

abstract = {Hybrid nanocomposites of nickel nanoparticles (Ni NPs) embedded in a carbon matrix hold significant promise for environmental remediation by integrating the adsorption capacity of carbon with the antimicrobial effects induced by localized heating of Ni NPs under magnetic hyperthermia. In this work, we investigate the evolution of the structural, magnetic and thermal properties of Ni@C nanocomposites as a function of the carbonization temperature. Samples within the magnetic single domain and multidomain regimes have been used to explore their potential for magnetic hyperthermia-assisted water remediation. To assess the influence of these different regimes on the tranverse suscepbility (TS) and magnetic heating performance, two representative samples, S600 and S1000, were selected to span the single-domain to multi-domain particle regimes. TS measurements show that S1000 exhibits a higher effective anisotropy field (HKeff), attributed to its larger particle size and enhanced magnetic anisotropy. However, calorimetric magnetic heating studies reveal that S600 demonstrates significantly higher specific absorption rate (SAR) and intrinsic loss power (ILP) values, especially at lower concentrations. This enhanced heating efficiency is linked to its smaller particle size, reduced dipolar interactions, and magnetically soft behavior at room temperature. Consequently, more effective magnetic relaxation under moderate fields is enabled, highlighting the importance of optimizing nanoparticle size, anisotropy, and matrix dispersion to improve magnetic heating performance, offering design strategies for non-biomedical applications such as water purification and microbial inactivation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{olayiwola_epitaxial_2025,

title = {Epitaxial D019-Mn3Ga thin films grown on the paramagnetic and diamagnetic MgO (111) substrate},

author = {Idris Opeyemi Olayiwola and Ricardo López and Rocío M. Gutiérrez-Pérez and Carlos R. Santillán-Rodríguez and Óscar O. Solís-Canto and Renee J. Sáenz-Hernández and José T. Holguín-Momaca and Sion F. Olive-Méndez},

url = {https://www.sciencedirect.com/science/article/pii/S2211379725003298},

doi = {10.1016/j.rinp.2025.108435},

issn = {2211-3797},

year  = {2025},

date = {2025-10-01},

urldate = {2025-11-12},

journal = {Results in Physics},

volume = {77},

pages = {108435},

abstract = {50 nm-thick D019-Mn3Ga epitaxial thin films were grown on MgO (111) substrates by rf-magnetron sputtering. Structural characterization demonstrated the single crystalline nature of the films grown at 400 and 500 °C, while those grown at 600 °C show an epitaxial mosaic-like growth together with the crystallization of the tetragonal D022 phase. The magnetic measurements evidenced the presence of diamagnetic and paramagnetic contributions due to the substrate, with the paramagnetic contribution probably due to magnetic impurities with concentration below 1 % atomic. We removed those contributions in both the magnetization-magnetic field and magnetization-temperature curves. After that correction, the magnetic loops of the D019-Mn3Ga thin films were decomposed in antiferromagnetic and ferromagnetic components, employing the Brillouin function, the latest arising from the canting of the magnetic moment of the Mn atoms and the distortion of the kagome spin structure, of the D019 phase, at the boundaries between single crystalline domains as well as the ferrimagnetic contribution of the D022 clusters.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{lopez_tuning_2024,

title = {Tuning of magnetic properties and giant magnetoimpedance effect in multilayered microwires},

author = {Ricardo López and J. P. Andrés and J. A. González and A. García-Gómez and V. Zhukova and A. Chizhik and M. Salaheldeen and A. Zhukov},

url = {https://www.sciencedirect.com/science/article/pii/S2468217924001527},

doi = {10.1016/j.jsamd.2024.100821},

issn = {2468-2179},

year  = {2024},

date = {2024-12-01},

urldate = {2024-12-13},

journal = {Journal of Science: Advanced Materials and Devices},

volume = {9},

number = {4},

pages = {100821},

abstract = {We studied the magnetic properties and Giant Magnetoimpedance (GMI) effect in amorphous Co-rich microwires with similar chemical compositions and different diameters with magnetic (Co, Permalloy) and non-magnetic (Cu) layers deposited by magnetic sputtering onto glass-coating. Studies of magnetic properties and GMI effect of as-prepared microwires and the same microwires with deposited magnetic and non-magnetic layers reveal substantial impact of such layers on GMI effect and hysteresis loops. Both as-prepared samples present soft magnetic properties and high GMI effect. The contribution of magnetic layers is observed in hysteresis loop at higher magnetic field, with hysteresis loops similar to those observed in microwires with mixed amorphous-crystalline structure. Meanwhile, both magnetic and non-magnetic layers affect low field hysteresis loops of both samples. Additionally, the GMI ratio, ΔZ/Z, and magnetic field dependences of GMI ratio are substantially affected by the presence of magnetic and non-magnetic layers deposited onto glass-coating. We discussed the observed experimental dependences considering both change of the internal stresses originated by the sputtered layer as well as the magnetostatic interaction between the amorphous ferromagnetic nucleus and deposited magnetic layers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pilati_mn-ferrite_2024,

title = {Mn-ferrite nanoparticles as promising magnetic tags for radiofrequency inductive detection and quantification in lateral flow assays},

author = {Vanessa Pilati and María Salvador and Leyre Bei Fraile and José Luis Marqués-Fernández and Franciscarlos Gomes da Silva and Mona Fadel and Ricardo López and María del Puerto Morales and José Carlos Martinez-García and Montserrat Rivas},

url = {https://pubs.rsc.org/en/content/articlelanding/2024/na/d4na00445k},

doi = {10.1039/D4NA00445K},

issn = {2516-0230},

year  = {2024},

date = {2024-08-01},

urldate = {2024-12-13},

journal = {Nanoscale Advances},

volume = {6},

number = {16},

pages = {4247–4258},

abstract = {Lateral flow assays are low-cost point-of-care devices that are stable, easy to use, and provide quick results. They are mostly used as qualitative screening tests to detect biomarkers for several diseases. Quantification of the biomarkers is sometimes desirable but challenging to achieve. Magnetic nanoparticles can be used as tags, providing both visual and magnetic signals that can be detected and quantified by magnetic sensors. In the present work, we synthesized superparamagnetic MnFe2O4 nanoparticles using the hydrothermal coprecipitation route. MnFe2O4 presents low magnetic anisotropy and high saturation magnetization, resulting in larger initial magnetic susceptibility, which is crucial for optimizing the signal in inductive sensors. We functionalized the coprecipitated nanoparticles with citric acid to achieve colloidal stability in a neutral pH and to provide carboxyl groups to their surface to bioconjugate with biomolecules, such as proteins and antibodies. The nanomaterials were characterized by several techniques, and we correlated their magnetic properties with their sensitivity and resolution for magnetic detection in radiofrequency inductive sensors. We considered the NeutrAvidin/biotin model of biorecognition to explore their potential as magnetic labels in lateral flow assays. Our results show that MnFe2O4 nanoparticles are more sensitive to inductive detection than magnetite nanoparticles, the most used nanotags in magnetic lateral flow assays. These nanoparticles present high potential as magnetic tags for the development of sensitive lateral flow immunoassays for detecting and quantifying biomarkers.},

note = {Publisher: RSC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salaheldeen_dependence_2024,

title = {Dependence of Magnetic Properties of As-Prepared Nanocrystalline Ni2MnGa Glass-Coated Microwires on the Geometrical Aspect Ratio},

author = {Mohamed Salaheldeen and Valentina Zhukova and Ricardo López and Arcady Zhukov},

url = {https://www.mdpi.com/1424-8220/24/11/3692},

doi = {10.3390/s24113692},

issn = {1424-8220},

year  = {2024},

date = {2024-01-01},

urldate = {2024-12-13},

journal = {Sensors},

volume = {24},

number = {11},

pages = {3692},

abstract = {We have prepared NiMnGa glass-coated microwires with different geometrical aspect ratios, ρ = dmetal/Dtotal (dmetal—diameter of metallic nucleus, and Dtotal—total diameter). The structure and magnetic properties are investigated in a wide range of temperatures and magnetic fields. The XRD analysis illustrates stable microstructure in the range of ρ from 0.25 to 0.60. The estimations of average grain size and crystalline phase content evidence a remarkable variation as the ρ-ratio sweeps from 0.25 to 0.60. Thus, the microwires with the lowest aspect ratio, i.e., ρ = 0.25, show the smallest average grain size and the highest crystalline phase content. This change in the microstructural properties correlates with dramatic changes in the magnetic properties. Hence, the sample with the lowest ρ-ratio exhibits an extremely high value of the coercivity, Hc, compared to the value for the sample with the largest ρ-ratio (2989 Oe and 10 Oe, respectively, i.e., almost 300 times higher). In addition, a similar trend is observed for the spontaneous exchange bias phenomena, with an exchange bias field, Hex, of 120 Oe for the sample with ρ = 0.25 compared to a Hex = 12.5 Oe for the sample with ρ = 0.60. However, the thermomagnetic curves (field-cooled—FC and field-heating—FH) show similar magnetic behavior for all the samples. Meanwhile, FC and FH curves measured at low magnetic fields show negative values for ρ = 0.25, whereas positive values are found for the other samples. The obtained results illustrate the substantial effect of the internal stresses on microstructure and magnetic properties, which leads to magnetic hardening of samples with low aspect ratio.},

note = {Number: 11 

Publisher: Multidisciplinary Digital Publishing Institute},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gutierrez-perez_high_2023,

title = {High Curie Temperature in Epitaxial D022–Mn3−xGa Ultrathin Films},

author = {Rocío M. Gutiérrez-Pérez and Ricardo López and José T. Holguín-Momaca and Sion F. Olive-Méndez},

url = {https://www.worldscientific.com/doi/10.1142/S2010324723400076},

doi = {10.1142/S2010324723400076},

issn = {2010-3247},

year  = {2023},

date = {2023-06-01},

urldate = {2024-12-13},

journal = {SPIN},

volume = {13},

number = {02},

pages = {2340007},

abstract = {The D0 

2 

2 

22 

–Mn3Ga ferrimagnet promises potential applications in spintronics due to its low magnetization, strong perpendicular magnetic anisotropy and high Curie temperature. In the form of thin and thick films, these properties are preserved. Here, we report on the structural and magnetic characterization of epitaxial D0 

2 

2 

22 

–Mn 

2 

. 

6 

2.6 

Ga ultrathin films with thicknesses of 2 

nm, 5 

nm and 8 

nm grown on Cr buffer layers by magnetron sputtering. We found that the films are perfect single crystals with flat surfaces and Curie temperatures higher than 300 

K. The 2 

nm-thick ultrathin film has higher magnetization than that of the thicker films, likely due to uncompensated ferrimagnetic planes, along the c-axis, linked to the surface roughness at the atomic scale. These properties highly suit the requirements for the elaboration of spintronic devices such as magnetic tunnel junctions.},

note = {Publisher: World Scientific Publishing Co.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salaheldeen_manipulation_2023,

title = {Manipulation of magnetic and structure properties of Ni2FeSi glass-coated microwires by annealing},

author = {M. Salaheldeen and A. Garcia-Gomez and P. Corte-Leon and A. Gonzalez and M. Ipatov and V. Zhukova and J. Gonzalez and Ricardo López and A. Zhukov},

url = {https://www.sciencedirect.com/science/article/pii/S0925838823003298},

doi = {10.1016/j.jallcom.2023.169026},

issn = {0925-8388},

year  = {2023},

date = {2023-05-01},

urldate = {2024-12-13},

journal = {Journal of Alloys and Compounds},

volume = {942},

pages = {169026},

abstract = {In the current work, we demonstrate that the magnetic and structural properties of Ni2FeSi glass-coated microwires are strongly dependent on annealing conditions. A noticeable change in the magnetic and structural properties has also been compared to as- prepared samples. Annealing conditions increase the crystalline phase content from 34% to 72% for annealing duration 1 h and 6 h, respectively. While as- prepared samples show square hysteresis loops for a wide range of measuring temperatures, annealed samples show inclined hysteresis loops shape. Additionally, a marked increase in coercive and magnetic anisotropy fields has been observed for annealed samples as compared to as- prepared ones at and below room temperature. Meanwhile, highly reduced magnetic remanence was measured in the as-prepared samples. Temperature dependence of the coercivity shows anomalous behavior for as-prepared and annealed samples as well. An increase in the magnetization of the metallic nuclei of Ni2FeSi glass-coated observed in annealed microwire has been attributed to the internal stresses relaxation caused by annealing. The anomalous magnetic behavior at low temperature is due to the coexistence of ordered and disordered phases induced by annealing conditions. The difference in magnetization behavior, remanence, and coercivity values for Ni2FeSi glass-coated microwires samples indicates the influence of internal stresses created by the presence of the glass coating. These findings reveal the sensitivity of Heusler-based glass-coated microwires to temperature and annealing conditions, which will open the door to the design of spintronic devices and sensing applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salaheldeen_enhancing_2023,

title = {Enhancing the Squareness and Bi-Phase Magnetic Switching of Co2FeSi Microwires for Sensing Application},

author = {Mohamed Salaheldeen and Asma Wederni and Mihail Ipatov and Valentina Zhukova and Ricardo López and Arcady Zhukov},

url = {https://www.mdpi.com/1424-8220/23/11/5109},

doi = {10.3390/s23115109},

issn = {1424-8220},

year  = {2023},

date = {2023-01-01},

urldate = {2024-12-13},

journal = {Sensors},

volume = {23},

number = {11},

pages = {5109},

abstract = {In the current study we have obtained Co2FeSi glass-coated microwires with different geometrical aspect ratios, ρ = d/Dtot (diameter of metallic nucleus, d and total diameter, Dtot). The structure and magnetic properties are investigated at a wide range of temperatures. XRD analysis illustrates a notable change in the microstructure by increasing the aspect ratio of Co2FeSi-glass-coated microwires. The amorphous structure is detected for the sample with the lowest aspect ratio (ρ = 0.23), whereas a growth of crystalline structure is observed in the other samples (aspect ratio ρ = 0.30 and 0.43). This change in the microstructure properties correlates with dramatic changing in magnetic properties. For the sample with the lowest ρ-ratio, non-perfect square loops are obtained with low normalized remanent magnetization. A notable enhancement in the squareness and coercivity are obtained by increasing ρ-ratio. Changing the internal stresses strongly affects the microstructure, resulting in a complex magnetic reversal process. The thermomagnetic curves show large irreversibility for the Co2FeSi with low ρ-ratio. Meanwhile, if we increase the ρ-ratio, the sample shows perfect ferromagnetic behavior without irreversibility. The current result illustrates the ability to control the microstructure and magnetic properties of Co2FeSi glass-coated microwires by changing only their geometric properties without performing any additional heat treatment. The modification of geometric parameters of Co2FeSi glass-coated microwires allows to obtain microwires that exhibit an unusual magnetization behavior that offers opportunities to understand the phenomena of various types of magnetic domain structures, which is essentially helpful for designing sensing devices based on thermal magnetization switching.},

note = {Number: 11 

Publisher: Multidisciplinary Digital Publishing Institute},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In unison magnetization reversal in a magnetoelastic bilayer structure},

author = {N. Cotón and J. P. Andrés and A. Cabrera and M. Maicas and R. Ranchal},

doi = {10.1063/5.0165537},

issn = {0021-8979},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Applied Physics},

volume = {134},

issue = {10},

publisher = {AIP Publishing},

abstract = {Due to the magnetostriction effect, a magnetic material changes its dimensions when it is magnetized. In this work, we show how in a magnetostrictive bilayer structure comprising two materials with magnetostriction constants of opposite signs, the magnetic switching is affected by magnetoelastic coupling. While the layer with positive magnetostriction tries to elongate in the direction of the applied magnetic field, the layer with negative magnetostriction tries to contract. In the studied bilayers, the mechanical influence of each magnetostrictive layer on the other is of the opposite sign because of their opposite magnetostrictive constants. Since magnetoelasticity is not an interfacial interaction but an intrinsic property of magnetic materials, the mechanical strain promoted by the applied magnetic field affects the layers as a whole. The net effect is a simultaneous reversal of magnetization of the two layers regardless of their thicknesses. This behavior has been studied in bilayers with different thickness ratios comprising Ni90Fe10, negative magnetostriction and Fe70Ga30, positive magnetostriction. These results demonstrate the possibility of using this physical mechanism to beat the critical limit thickness imposed by interfacial interactions in magnetically coupled multilayers in such a way that the magnetization reversal is made in unison regardless of the layer thickness.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Stripe domains in electrodeposited Ni90Fe10 thin films},

author = {N. Cotón and J. P. Andrés and E. Molina and M. Jaafar and R. Ranchal},

doi = {10.1016/j.jmmm.2022.170246},

issn = {03048853},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Magnetism and Magnetic Materials},

volume = {565},

publisher = {Elsevier B.V.},

abstract = {Here we have investigated the formation of stripe domains in electrodeposited Ni90Fe10 films, a metallic alloy with relevant magnetoelastic properties. The X-ray diffractometry patterns confirm the deposition of NiFe with an experimental lattice parameter close to the theoretical value. We have analyzed the influence of both magnetic stirring and an applied magnetic field perpendicular to the sample plane on the formation of stripe domains in Ni90Fe10 films. It is observed the characteristic fingerprint of stripe domains, i.e. the transcritical shape in the in-plane hysteresis loops when the electrolyte is not magnetically stirred during electrodeposition. The quality factor reveals a moderate perpendicular magnetic anisotropy which is confirmed by the stripe periodicity inferred by Magnetic Force Microscopy. In particular, stripe domains are only visible by this technique when the sample thickness is well above the theoretical critical thickness for the stripe domains to be formed. Finally, in samples released after being grown in outward bent flexible substrates it has been promoted an induced in-plane magnetoelastic magnetic anisotropy that reduces the perpendicular magnetic anisotropy. The high quality of the samples studied in this work from the magnetoelastic point of view is reflected by the magnetostriction constant of −22 ppm that it has been experimentally inferred.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{gutierrez-perez_strong_2022,

title = {Strong perpendicular magnetic anisotropy in epitaxial D022-Mn3+xGa ultrathin films},

author = {Rocío M. Gutiérrez-Pérez and Diego I. Zubiate-Pérez and Ricardo López and Maria E. Fuentes-Montero and José T. Holguín-Momaca and Óscar O. Solís-Canto and Adriana Alvídrez-Lechuga and J. A. González and Sion F. Olive-Méndez},

url = {https://www.sciencedirect.com/science/article/pii/S2468023022006885},

doi = {10.1016/j.surfin.2022.102427},

issn = {2468-0230},

year  = {2022},

date = {2022-12-01},

urldate = {2024-12-13},

journal = {Surfaces and Interfaces},

volume = {35},

pages = {102427},

abstract = {Ferrimagnets are highly sought-after materials thanks to their strong perpendicular magnetic anisotropy (PMA) and low magnetization. For example, they are promising materials for current-induced magnetization switching applications. Ferrimagnetic D022-Mn3Ga integrates these properties with a low damping constant and a high Curie temperature. Here, we report a complete analysis of the magnetization and the effective PMA evolution with the thickness of the epitaxial D022-Mn3+xGa ultrathin films. The crystals were grown by magnetron sputtering following two methods: reactive deposition epitaxy and solid phase epitaxy. We found that the uniaxial PMAs and the thickness of the dead magnetic layers differ strongly upon the employed growth method, while saturation magnetizations remain unchanged. Structural defects at the interface due to lattice mismatch and growth method, explain our results. We expose objective estimations of the thermal stability factor Δ, based on the effective PMA in the ultrathin film context. Taking into account our results, D022-Mn3+xGa, in this form, can be employed as the free layer on magnetic tunnel junctions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{robles-cuenca_miniature_2022,

title = {Miniature Autonomous Robot Based on Legged In-Plane Piezoelectric Resonators with Onboard Power and Control},

author = {David Robles-Cuenca and Mario Rodolfo Ramírez-Palma and Víctor Ruiz-Díez and Jorge Hernando-García and José Luis Sánchez-Rojas},

url = {https://www.mdpi.com/2072-666X/13/11/1815},

doi = {10.3390/mi13111815},

issn = {2072-666X},

year  = {2022},

date = {2022-11-01},

urldate = {2023-05-29},

journal = {Micromachines},

volume = {13},

number = {11},

pages = {1815},

abstract = {This work reports the design, fabrication, and characterization of a centimetre-scale autonomous robot with locomotion based on in-plane piezoelectric resonators and 3D-printed inclined legs. The robot consists of a pair of cooperative piezoelectric motors, an electronic power circuit and a battery-powered microcontroller. The piezoelectric motors feature a lead zirconate titanate (PZT) plate of dimensions 20 mm × 3 mm × 0.2 mm vibrating on its first extensional resonant mode at around 70 kHz. A particular position of 3D-printed inclined legs allowed the conversion of the in-plane movement into an effective forward thrust. To enable arbitrary trajectories of the robot on a surface, two parallel piezoelectric plate motors were arranged in a differential drive scheme. The signals to excite these plates were generated by the microcontroller and adapted by a supplementary electronic circuit to increase the effective voltage supplied by the onboard battery. The fully assembled robot had a size of 27 mm × 15 mm and a weight of 7 g and reached a linear speed of approximately 15 mm/s and a rotational speed of up to 50 deg./s. Finally, the autonomous robot demonstrated the ability to follow pre-programmed paths.},

note = {Number: 11 

Publisher: Multidisciplinary Digital Publishing Institute},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{umoh_influence_2022,

title = {Influence of textitex-situ thermal treatment on the chemical states, microstructure and ferroelectrics properties of polycrystalline BiMnO3-δ thin films},

author = {G. V. Umoh and J. T. Holguín-Momaca and R. P. Talamantes and G. Rojas-George and G. Herrera-Pérez and Ricardo López and Francisco Servando Aguirre-Tostado and O. Auciello and S. F. Olive-Méndez and A. Hurtado-Macias},

url = {https://www.sciencedirect.com/science/article/pii/S0040609022002760},

doi = {10.1016/j.tsf.2022.139362},

issn = {0040-6090},

year  = {2022},

date = {2022-08-01},

urldate = {2024-12-13},

journal = {Thin Solid Films},

volume = {756},

pages = {139362},

abstract = {Nanoelectronic devices based on oxide films require materials that may exhibit combined properties such as ferroelectricity, ferromagnetism, and/or ferroelasticity at the same phase. In this sense, multiferroic perovskite BiMnO3-δ thin films exhibit a relevant combination of ferroelectricity and ferromagnetism suitable for device applications. The purpose of this work is to investigate the growth conditions of BiMnO3 thin films using radio-frequency magnetron sputtering and the role of ex-situ thermal treatments under different conditions, which resulted in a P21/c to C2 phase transformation and BiMnO2.93 composition. The crystal structure of the BiMnO3-δ thin films was investigated using X-ray diffraction, high-resolution transmission electron microscopy, ultraviolet-visible spectrophotometer, X-ray photoelectron spectroscopy, and resistivity measurement, to correlate structural and transport properties. The ex-situ thermal treatment was performed in a bismuth and oxygen atmosphere in order to compensate for Bi and O deficiencies. Thus, the result was not an ideal stoichiometric, BiMnO3-δ proved to enhance the ferroelectric properties and other physical properties. The optimized thin films exhibit ferromagnetism up to 37 K, while ferroelectricity remains up to room temperature.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Salaheldeen2022,

title = {Enhancement of Exchange Bias and Perpendicular Magnetic Anisotropy in CoO/Co Multilayer Thin Films by Tuning the Alumina Template Nanohole Size},

author = {Mohamed Salaheldeen and Ayman Nafady and Ahmed M. Abu-Dief and Rosario Díaz Crespo and María Paz Fernández-García and J. P. Andrés and Ricardo López and Jesús A. Blanco and Pablo Álvarez-Alonso},

doi = {10.3390/nano12152544},

issn = {20794991},

year  = {2022},

date = {2022-01-01},

journal = {Nanomaterials},

volume = {12},

issue = {15},

publisher = {MDPI},

abstract = {The interest in magnetic nanostructures exhibiting perpendicular magnetic anisotropy and exchange bias (EB) effect has increased in recent years owing to their applications in a new generation of spintronic devices that combine several functionalities. We present a nanofabrication process used to induce a significant out-of-plane component of the magnetic easy axis and EB. In this study, 30 nm thick CoO/Co multilayers were deposited on nanostructured alumina templates with a broad range of pore diameters, 34 nm ≤ Dp ≤ 96 nm, maintaining the hexagonal lattice parameter at 107 nm. Increase of the exchange bias field (HEB) and the coercivity (HC) (12 times and 27 times, respectively) was observed in the nanostructured films compared to the non-patterned film. The marked dependence of HEB and HC with antidot hole diameters pinpoints an in-plane to out-of-plane changeover of the magnetic anisotropy at a nanohole diameter of ∼75 nm. Micromagnetic simulation shows the existence of antiferromagnetic layers that generate an exceptional magnetic configuration around the holes, named as antivortex-state. This configuration induces extra high-energy superdomain walls for edge-to-edge distance >27 nm and high-energy stripe magnetic domains below 27 nm, which could play an important role in the change of the magnetic easy axis towards the perpendicular direction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{deltell_martensitic_2021,

title = {Martensitic transformation, magnetic and magnetocaloric properties of Ni–Mn–Fe–Sn Heusler ribbons},

author = {A. Deltell and Abd El-Moez A. Mohamed and P. Álvarez-Alonso and M. Ipatov and J. P. Andrés and J. A. González and T. Sánchez and A. Zhukov and M. L. Escoda and J. J. Suñol and Ricardo López},

url = {https://www.sciencedirect.com/science/article/pii/S2238785421002763},

doi = {10.1016/j.jmrt.2021.03.049},

issn = {2238-7854},

year  = {2021},

date = {2021-05-01},

urldate = {2024-12-13},

journal = {Journal of Materials Research and Technology},

volume = {12},

pages = {1091–1103},

abstract = {Melt-spun ribbons of nominal composition Ni50Mn36-xFexSn14 (x = 0, 2, and 3) were prepared by melt-spinning. The alloys undergo a martensitic transformation from L21 austenite to an orthorhombic 4O martensite on cooling, as determined by X-ray powder diffraction analysis. Replacement of Mn by Fe linearly reduces the characteristic temperatures of the martensitic transformation (the equilibrium temperature decreases from 328 to 285 K) and reduces the Curie temperature of the austenite phase (from 336 to 300 K), whereas the effect of the applied magnetic field on the martensite transition temperatures is negligible. Magnetic measurements (zero-field cooled, ZFC, and field cooled, FC, curves, AC susceptibility measurements) hint the coexistence of two different ferromagnetic martensitic magnetic phases. Moreover, the AC susceptibility measurements and the irreversibility of the ZFC and FC curves point towards the presence of antiferromagnetic and ferromagnetic interactions in the martensitic phase. All samples exhibit spontaneous exchange bias at 2 K, with double-shifted loops, whereas the evolution of the conventional exchange bias with the temperature agrees quite well with the behavior of ferromagnetic regions surrounded by spin-glass regions or with the coexistence of ferromagnetic–antiferromagnetic interactions. Ni50Mn36-xFexSn14 ribbons present a moderate inverse magnetocaloric effect (with a maximum of the magnetic entropy change of 5.7 Jkg−1K−1 for μ0H = 3 T for x = 3). It is worth to note that these materials feature a significant reservoir (up to 44 Jkg−1K−1 for x = 2) of magnetic entropy change, linked to the proximity of the austenitic ferromagnetic transition to the martensitic transformation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}