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Scientific publication by ULTIMATE-I researchers from CNEA-CONICET Argentina and CIC nanoGUNE BRTA San Sebastian, Spain: « Magnetization reversal phenomena in thin films presenting stripe domain »

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.

Available at SSRN: https://ssrn.com/abstract=4548057 or http://dx.doi.org/10.2139/ssrn.4548057

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Scientific publication by ULTIMATE-I researchers from CNEA-CONICET Argentina and University of Zaragoza Spain: “Annealing effects on the magnetic and magnetotransport properties of iron oxide nanoparticles self-assemblies”

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.

Nanotechnology, Volume 34, Number 45

DOI: 10.1088/1361-6528/aced0e

Repository link

All Open Access, Green Submitted

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Scientific publication by ULTIMATE-I researchers from ICN2 Spain and USM Chile: “Antisite defects and chemical expansion in low-damping, high-magnetization yttrium iron garnet films”

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.

ChemNanoMat 2022, e20220

DOI: 10.1002/cnma.202200495

Repository link

All Open Access, Gold-Hybrid, Green Published

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Poster presentations at JEMS 2023, Madrid (Spain)

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

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Meeting of Marie Skłodowska-Curie Research and Innovation Staff Exchange (MSCA-RISE) participants in INMA

The second is the meeting between ULTIMATE-I and NESTOR, both Research and Innovation Staff Exchange (RISE) projects from Marie Skłodowska-Curie Action involving researchers from Spain and Argentina, amount other countries, from left to right: Alejandro Butera, Myriam Aguirre (both ULTIMATE-I) and Gerardo Goya and Enio Lima Jr (NESTOR), both RISE project at Instituto de Nanociencia y Materiales de Aragón (INMA).

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Ferromagnetic films on ferroelectric substrates seminar by Alejandro Butera (CONICET)

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.

https://inma.unizar-csic.es/en/agenda-eventos/inma-seminar-alejandro-butera/

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Vanina Gisela Franco from CONICET Argentina presents her work about thermoelectric material prepared from natural pyrite

Iberian Thermoelectric Workshop – ITW ’23 Lisbon was hosted at Campus Tecnológico e Nuclear of IST-UL, Lisbon, from March 30-31 2023. The conference aims to provide opportunities to improve the collaboration between researchers and specialists in the thermoelectricity field and also allow an open discussion about the most recent advances in materials, properties measurement, module fabrication, and device applications.

Dra. Vanina Gisela Franco from Instituto de Física del Litoral IFIS-CONICET, Santa Fe, Argentina used her secondment to the University of Zaragoza to present her work on this exciting topic done in the scope of the ULTIMATE I project.

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Alejandro Butera from CNEA Magnetic Resonance Laboratory secondment to the University of Zaragoza

Alejandro Butera, CONICET professor and researcher of CNEA Magnetic Resonance Laboratory, from the Instituto Balseiro de San Carlos de Bariloche-Argentina is visiting the Advanced Microscopy Laboratory (LMA) of the University of Zaragoza-Spain (UNIZAR) and Aragón Materials Science Institute (ICMA).

During his stay, he will study FeCo and permalloy samples prepared by focused ion beam (FIB) and use transmission electron microscope (TEM) analysis by Titan TEM.

Alejandro Butera and Teobaldo Torres are in pictures preparing to enter the Clean Room for using the Dual Beam 650 and lamellae preparation.