arXiv subjects

L. Avilés-Félix

Publications and source records attributed to L. Avilés-Félix.

6 recordsLinked to original sources

arXiv2026

In-plane magnetic field control of anomalous Hall response enabled by magnetic anisotropy engineering

Engineering magnetic anisotropy provides a powerful route to control magnetization orientation and unlock emerging functionalities in opto-spintronic and current-driven devices. Beyond its role in magnetization reversal, the effective anisotropy can strongly influence the magnetotransport response, offering an additional degree of freedom to tune new device functionalities. In this work, we report a magnetotransport study of a ferrimagnetic [Tb/Co]$_{\times 5}$ multilayer grown with a Tb thickness gradient, whose wedge-shaped tilts the uniaxial anisotropy axis slightly away from the film normal. Anomalous Hall resistivity measurements from 80 K to 300 K reveal a spin reorientation transition, while the angular dependence of the magnetotransport responses exposes the crucial role of the tilted anisotropy. A simplified macrospin model reproduces the full angular response across the transition and shows that the observed anomalous Hall effect when the in-plane magnetic field is applied originates from the tilt of the uniaxial anisotropy axis, which supplies a built-in symmetry-breaking mechanism, enabling in-plane field control over the out-of-plane anomalous Hall response, sign included. These findings establish tilted magnetic anisotropy as a promising route toward Hall effect-based sensor applications and highlight Tb/Co multilayers as a versatile platform for anisotropy-engineered spintronic devices.

cond-mat.mes-hall↗

arXiv2026

Macroscopic evidence of spatial modulation of conductivity in a microtextured ferromagnetic film

A 75 nm-thick Fe0.5Pt0.5 film is a ferromagnetic metal showing striped magnetic domains in remanence at room temperature. The magnetoresistance is characterized by varying the external temperature and the in-plane magnetic field intensity, thereby affecting its magnetic structure. Qualitatively, the resistivity is well described by using the generalized Ohm's law. High-field magnetotransport properties are successfully explained by considering the competition between the expected metallic behavior and the electron-magnon interaction. In the low-field condition, we size the contribution of the magnetic texture to the macroscopic magnetotransport response by introducing a new quantity. Consistent with the microscopic modulation of the lateral conduction, low-field measurements reveal inhomogeneities attributed to the spatial distribution of ferromagnetic domains and domain walls. By carefully analyzing the macroscopic response near the coercive field, the additional contribution to the resistivity is attributed to the domain walls themselves. In fact, this term could surpass the anisotropic term at low temperatures. In summary, this study demonstrates that spatial magnetic inhomogeneities are not only macroscopically measurable but also comparable in magnitude to other regularly considered terms, mainly at low temperatures.

cond-mat.mes-hall↗

arXiv2026

Perpendicularly magnetized Tb/Co multilayers featuring tilted uniaxial anisotropy: Experiments and modeling

Rare earth/transition metal (RE/TM) multilayers with perpendicular magnetic anisotropy are key ingredients for the development of spintronic applications. Their compensation temperature depends on the ratio of the thicknesses of rare earth and transition metal, allowing their magnetic properties to be tuned with temperature while maintaining their anisotropy even in nanometer-scale devices. In this work, we performed a thorough structural characterization and systematically investigate the magnetic properties of a whole family of ferrimagnetic [Tb/Co]$_{\times 5}$ multilayers varying the Tb thickness in the range of 0.4 nm - 1.25 nm. A linear dependence of the compensation temperature on the Tb layer thickness was observed. Moreover, a uniaxial anisotropy constant of 330$\pm$30 kJ/m$^3$, which is close to the values reported by other authors, was estimated. Additionally, we proposed a model to gain a better understanding of the angular dependence of the magnetization loops and the linear dependence of the compensation temperature. We present strong evidence demonstrating that the perpendicular anisotropy must be tilted away from the perpendicular axis in order to explain the observed features, particularly the hysteresis in the in-plane loops. Our work advances the understanding of DC magnetic properties in thin RE/TM ferrimagnetic films, which has the potential to impact different fields where these materials are involved.

cond-mat.mtrl-sci↗

arXiv2025

Temperature and crystallographic orientation dependence of the anisotropic magnetoresistance in epitaxial Fe65Co35 thin films

In this work, we study the anisotropic magnetoresistance (AMR) behavior of [001] epitaxial Fe65Co35 thin films along different crystallographic directions as a function of temperature. The AMR ratio is found to strongly depend on the current orientation relative to the crystal axes, reaching 0.16 % and 0.10 % at room temperature when the current is applied along the magnetic hard and easy axes, respectively. Moreover, the AMR ratio decreases at different rates as the temperature is reduced to 80 K. The longitudinal and transverse magnetoresistance curves were fitted using the Stoner-Wohlfarth formalism to describe the magnetization reversal path and to extract the magnetic anisotropy constants. The fitted cubic and uniaxial anisotropy constants are Kc = -2.36 kJ/m3 and Ku = 2.18 kJ/m3, verifying the change in the cubic anisotropy compared to Fe-richer Fe100-xCox compositions. These results demonstrate that by tailoring the crystalline orientation and temperature dependence of AMR, epitaxial Fe65Co35 thin films can enable the design of magnetic sensors with tunable sensitivity.

cond-mat.mtrl-sci↗

arXiv2025

Magnetization process in epitaxial Fe$_{85}$Co$_{15}$ thin films via anisotropic magnetoresistance

The effects of the crystalline symmetry on the magnetotransport properties in ferromagnetic alloys are being reexamined in recent years particularly due to the role of the anisotropic magnetoresistance on the electrical detection of magnetization dynamics, which is relevant to estimate spin transport parameters such as the spin Hall angle or the damping constant. In this work we investigated the crystalline dependent anisotropic magnetoresistance in epitaxial Fe85Co15 films and discuss the magnetization process through the magnetotransport properties by varying the relative orientations between the electric current, the external magnetic field and the Fe85Co15 crystallographic directions. We have found that the anisotropic magnetoresistance ratio depends on the current direction with respect to the crystal axes of Fe85Co15 and determine a ratio of 0.20 % and 0.17 % when the current is applied along the [110] hard and [100] easy axes, respectively. We fit our experimental data using the Stoner-Wohlfarth model to describe the path followed by the magnetization during the magnetization process and to extract the anisotropy constants. The fitted cubic and uniaxial anisotropy constants are Kc = 21 kJ/m3 and Ku = 11 kJ/m3, which are comparable with reported values from the angular variation of ferromagnetic resonance experiments. Our results contribute to the understanding of the interplay between the crystalline structure and the magnetotransport properties of FeCo alloys.

cond-mat.mtrl-sci↗

arXiv2025

Self-induced spin pumping and inverse spin Hall effect in single FePt thin films

In this study, we investigate the spin-charge current conversion characteristics of chemically disordered ferromagnetic single FePt thin films by spin-pumping ferromagnetic resonance experiments performed on both a resonance cavity and on patterned devices. We clearly observe a self-induced signal in a single FePt layer. The sign of a single FePt spin pumping voltage signal is consistent with a typical bilayer with a positive spin Hall angle layer such as that of Pt on top of a ferromagnet (FM), substrate//FM/Pt. Structural analysis shows a strong composition gradient due to natural oxidation at both FePt interfaces, with the Si substrate and with the air. The FePt-thickness dependence of the self-induced charge current produced allowed us to obtain $λ_ \text{FePt}=(1.5\pm 0.1)$ nm and self-induced $θ_ \text{self-FePt}=0.047 \pm 0.003$, with efficiency for reciprocal effects applications $θ_ \text{self-FePt} \times λ_ \text{FePt} = 0.071$ nm which is comparable to that of Pt, $θ_ \text{SH-Pt} \times λ_ \text{Pt} = 0.2$ nm. Moreover, by studying bilayer systems such as Si//FePt/Pt and Si//Pt//FePt we independently could extract the individual contributions of the external inverse spin Hall effect of Pt and the self-induced inverse spin Hall effect of FePt. Notably, this method gives consistent values of charge currents produced due to only self-induced inverse spin Hall effect in FePt layers. These results advance our understanding of spin-to-charge interconversion mechanisms in composite thin films and pave the way for the development of next-generation spintronics devices based on self-torque.

cond-mat.mtrl-sci↗