Dr Mario C.G. Passeggi director of the Surface Physics Group of the Institute of Technological Development for the Chemical Industry (INTEC, CONICET, Argentina) made a secondment to the University of Zaragoza/INMA in the framework of the Ultimate I project. The research lines of his group are directed at studying the surface properties of materials comprising both the surface physics and interfaces laboratories and the theoretical physics of surfaces. The second included meetings with Spanish researchers, evaluation of the ESR research already done in the past two years of the project, and setting precise targets for the remaining project period.
The Surface Physics Group is part of the Institute, the Instituto de Física del Litoral (IFIS Litoral), maintaining the double dependence on CONICET and the Universidad Nacional del Litoral.
The authors present a study of properties related to the magnetization reversal process in two thin film samples presenting magnetic stripe domains: Fe0.82Ga0.18 (Fe-Ga) and Ni0.81Fe0.19 (permalloy). In Fe-Ga thin films, they focus on the magnetization reversal driven by thermal activation, by considering the magnetic viscosity behavior. The results suggest that the reversal process occurs gradually, where the magnetization switches direction via ~10 nm-long jumps of the magnetic domain walls. On the other hand, vectorial hysteresis loops were performed in permalloy thin films with the aim of studying the behavior of the transverse magnetization component (perpendicular to the applied field) during the magnetization reversal process. They show that the measurement of the transversal magnetization component shows a much higher sensitivity for the determination of the in-plane magnetic anisotropy than the usual hysteresis loops where the magnetization is parallel to the applied field. Moreover, this allows them to highlight the competition between the intrinsic and rotatable anisotropies in thin film-present stripe domains.
P. López Duque, D. Goijman, A. Sarmiento, G. Ramírez, L. Avilés-Félix, J. Gómez, M. Eddrief, A. Butera, P. Vavassori, and J. Milano, and D. Niebieskikwiat, Magnetization Reversal Phenomena in Thin Films Presenting Stripe Domains.
Fernando Fabris, Enio Lima Jr. (CNEA-CONICET), Jorge Martín Núñez (CNEA), Horacio E Troiani, Myriam H Aguirre (UniZar), Víctor Leborán, Francisco Rivadulla, Elin L. Winkler (CNEA-CONICET)
In magnetic tunnel junctions based on iron oxide nanoparticles, the disorder and the oxidation state of the surface spin as well as the nanoparticles functionalization play a crucial role in the magnetotransport properties. We report a systematic study of the effects of vacuum annealing on the structural, magnetic, and transport properties of self-assembled ∼10 nm Fe3O4 nanoparticles. This work shows new insights into the influence of the nanoparticle interfacial composition, as well as their spatial arrangement, on the tunnel transport of self-assemblies, and evidence of the importance of optimizing the nanostructure fabrication for increasing the tunneling current without degrading the spin-polarized current.
Dr. José Santiso (ICN2), Dr. Carlos García (USM), Dr. Cristian Romanque (USM), Dr. Loïc Henry, Dr. Nicolas Bernier, Dr. Núria Bagués, Dr. José Manuel Caicedo (ICN2), Dr. Manuel Valvidares, Dr. Felip Sandiumenge
Nanoscale epitaxial yttrium iron garnet films still pose fundamental issues regarding their interfacial behavior and impact on magnetic properties. This work shows interfacial yttrium accumulation forming octahedral antisite defects. The resulting suppression of magnetic moment from the minority sublattice results in an increased saturation magnetization. These results suggest a strong impact of unbalanced interdiffusion on magnetic behavior.
JEMS 2023, 27th Aug. to 1st Sep. 2023, Madrid (Spain)
Luis Avilés (CNEA): “Spin transport and magnetic dynamics in ultra low damping epitaxial Co100-xFex/Ta bilayers”; authors: D. Velázquez Rodríguez, J.E. Gómez, T.E. Torres, M.H. Aguirre J. Milano, P. Costanzo, L. Avilés-Félix, A. Butera
Lara Solís (CNEA): “Temperature-dependence of ferromagnetic resonance in YIG garnets thin films”; authors: Lara M. Solís, Santiago Carreira, Javier Briático, Abdelmadjid Anane, Myriam H. Aguirre, Laura Steren
Myriam Aguirre (UNIZAR): “Synthesis of magnetite from natural pyrite for energy conversion devices”; authors: Vanina G. Franco, Adriana E. Candia, Jorge M. Núñez, Miguel Rengifo, Myriam H. Aguirre
Santiago D. Barrionuevo, Federico Fioravanti, Jorge M. Núñez, Mauricio Llaver, Myriam H. Aguirre, Martín G. Bellino, Gabriela L. Laconi, Francisco J. Ibáñez
INMA Seminar: Ferromagnetic films on ferroelectric substrates – Alejandro Butera
The INMA Seminar and RISE-ULTIMATE-I Project hosted a seminar entitled “Ferromagnetic films on ferroelectric substrates”. The seminar willtake place on 17 April 2023. The session was given by the CONICET professor and researcher Alejandro Butera, from the Instituto Balseiro de San Carlos de Bariloche-Argentina.
The seminar took place on Monday 17 April at 12h in the Aula del Edificio I+D+I, 1st floor, Campus Río Ebro.
Summary: We present a study of the effects of applying an electric field on the magnetic response of Fe89Ga11 thin films deposited on PMN-PT (011) and (001) single-crystal ferroelectric substrates. Upon application of an electric field, we have observed that the M vs.H hysteresis loops are modified in the films grown on PMN-PT (011) crystals, consistent with a positive magnetostriction constant that depends on the film thickness. From ferromagnetic resonance experiments at 9.5 GHz, we obtained a thickness-dependent magnetoelectric constant in substrates (011), with a maximum dH/dE ~150 Oe.m/MV for t = 28 nm, consistent with estimates made from M vs. H loops.
We find that the facile magnetisation direction can be rotated by 90° with the application of an electric field only for 28 nm films deposited on PMN-PT (011). In thinner films, the magnetoelectric coefficient is too small to overcome the magnetic anisotropy. These results indicate that if magnetostrictive materials are to be applied in straintronics devices, the dependence of magnetic parameters on film thickness must be taken into account for optimal performance.
I will also give a summary of other topics we are investigating in the Magnetic Films group of the Magnetic Resonance Division – Bariloche, Argentina.
Authors: María Julia Jiménez, Livio Leiva, J.L. Ampuero Torres, G. Cabeza, J.E. Gómez, D. Velázquez Rodriguez, J. Milano, and A. Butera (presenter) from Laboratory of Magnetic Resonance Imaging, Bariloche Atomic Centre and Balseiro Institute, Bariloche, Argentina.
