Claudio Gonzalez-Fuentes

Bio: Claudio Gonzalez-Fuentes is an academic researcher from Federico Santa María Technical University. The author has contributed to research in topics: Scattering & Electrical resistivity and conductivity. The author has an hindex of 9, co-authored 23 publications receiving 234 citations. Previous affiliations of Claudio Gonzalez-Fuentes include Valparaiso University & University of Chile.

Magnetism and spin transport in rare-earth-rich epitaxial terbium and europium iron garnet films

Abstract: Rare-earth iron garnet thin films with perpendicular magnetic anisotropy (PMA) have recently attracted a great deal of attention for spintronic applications. Thulium iron garnet (TmIG) has been successfully grown and TmIG/Pt heterostructures have been characterized. However, TmIG is not the only rare-earth iron garnet that can be grown with PMA. We report the growth, magnetic, and spintronic properties of epitaxial terbium iron garnet (TbIG) and europium iron garnet (EuIG) thin films with PMA. Reciprocal space mapping shows the films are lattice matched to the substrate without strain relaxation, even for films up to 56 nm thick. The lattice strain and magnetostriction coefficient produce PMA in certain cases. TbIG grows on (111) gadolinium gallium garnet (GGG) with PMA due to the in-plane compressive strain, whereas TbIG on (111) substituted GGG (SGGG) is in tension and has an in-plane easy axis. EuIG grows with PMA on (100) and (111) GGG substrates, which facilitates the investigation of spintronic properties as a function of orientation. Both garnets have excess rare earth, which is believed to occupy Fe octahedral sites and in the case of TbIG is associated with an increase in the compensation temperature to 330 K, higher than the bulk value. Anomalous Hall effect (AHE) measurements of Pt/EuIG Hall crosses show that the spin mixing conductance of Pt/ (111) and (100) EuIG is similar. AHE measurements of Pt/TbIG Hall crosses reveal a sign change in the AHE amplitude at the compensation point analogous to all-metallic systems.

Spin-wave non-reciprocity in magnetization-graded ferromagnetic films

Abstract: A theoretical approach has been developed to study the spin-wave dynamics of magnetization-graded ferromagnetic films, where the magnetic properties change along the film thickness. The theory is based on a multilayer approach, where the influence of both long-range dipolar interactions and interlayer exchange coupling between sublayers is included. This allows for instance to describe films with a continuous variation of the saturation magnetization along the thickness. A systematic study is carried out in order to analyze different profiles of the saturation magnetization, which is checked through a test of convergence. It is found that the spin-wave dispersion is significantly modified when the strength of the magnetization changes in the bulk film, where a notable frequency non-reciprocity of two counter propagating spin waves is predicted. This is associated with heterosymmetric mode profiles and a modification of the conventional quantization condition associated to perpendicular standing spin-wave modes. Micromagnetic simulations have been carried out to validate the model, where a perfect agreement is reached between both methods. These results show that magnetization-graded ferromagnetic films can be used to channel and control spin waves, thus promoting different kinds of functionalities for magnon-based devices.

Magnetism and spin transport in rare-earth-rich epitaxial terbium and europium iron garnet films

Abstract: Rare-earth iron garnet thin films with perpendicular magnetic anisotropy (PMA) have recently attracted a great deal of attention for spintronic applications. Thulium iron garnet (TmIG) has been successfully grown and TmIG/Pt heterostructures have been characterized. However, TmIG is not the only rare-earth iron garnet that can be grown with PMA. We report the growth, magnetic, and spintronic properties of epitaxial terbium iron garnet (TbIG) and europium iron garnet (EuIG) thin films with PMA. Reciprocal space mapping shows the films are lattice matched to the substrate without strain relaxation, even for films up to 56 nm thick. The lattice strain and magnetostriction coefficient produce PMA in certain cases. TbIG grows on (111) gadolinium gallium garnet (GGG) with PMA due to the in-plane compressive strain, whereas TbIG on (111) substituted GGG (SGGG) is in tension and has an in-plane easy axis. EuIG grows with PMA on (100) and (111) GGG substrates, which facilitates the investigation of spintronic properties as a function of orientation. Both garnets have excess rare earth, which is believed to occupy Fe octahedral sites and in the case of TbIG is associated with an increase in the compensation temperature to 330 K, higher than the bulk value. Anomalous Hall effect (AHE) measurements of Pt/EuIG Hall crosses show that the spin mixing conductance of Pt/ (111) and (100) EuIG is similar. AHE measurements of Pt/TbIG Hall crosses reveal a sign change in the AHE amplitude at the compensation point analogous to all-metallic systems.

Quantitative study of the spin Hall magnetoresistance in ferromagnetic insulator/normal metal hybrids

Abstract: We experimentally investigate and quantitatively analyze the spin Hall magnetoresistance effect in ferromagnetic insulator/platinum and ferromagnetic insulator/nonferromagnetic metal/platinum hybrid structures. For the ferromagnetic insulator, we use either yttrium iron garnet, nickel ferrite, or magnetite and for the nonferromagnet, copper or gold. The spin Hall magnetoresistance effect is theoretically ascribed to the combined action of spin Hall and inverse spin Hall effect in the platinum metal top layer. It therefore should characteristically depend upon the orientation of the magnetization in the adjacent ferromagnet and prevail even if an additional, nonferromagnetic metal layer is inserted between Pt and the ferromagnet. Our experimental data corroborate these theoretical conjectures. Using the spin Hall magnetoresistance theory to analyze our data, we extract the spin Hall angle and the spin diffusion length in platinum. For a spin-mixing conductance of 4×1014 ??1m?2, we obtain a spin Hall angle of 0.11±0.08 and a spin diffusion length of (1.5±0.5) nm for Pt in our thin-film samples

The 2021 Magnonics Roadmap.

Abstract: Magnonics is a rather young physics research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. After several papers and review articles published in the last decade, with a steadily increase in the number of citations, we are presenting the first Roadmap on Magnonics. This a collection of 22 sections written by leading experts in this field who review and discuss the current status but also present their vision of future perspectives. Today, the principal challenges in applied magnonics are the excitation of sub-100 nm wavelength magnons, their manipulation on the nanoscale and the creation of sub-micrometre devices using low-Gilbert damping magnetic materials and the interconnections to standard electronics. In this respect, magnonics offers lower energy consumption, easier integrability and compatibility with CMOS structure, reprogrammability, shorter wavelength, smaller device features, anisotropic properties, negative group velocity, non-reciprocity and efficient tunability by various external stimuli to name a few. Hence, despite being a young research field, magnonics has come a long way since its early inception. This Roadmap represents a milestone for future emerging research directions in magnonics and hopefully it will be followed by a series of articles on the same topic.