Spin-flop led peculiar behavior of temperature-dependent anomalous Hall effect in Hf/Gd-Fe-Co

TL;DR

This study explores the temperature-dependent anomalous Hall effect in Hf/Gd-Fe-Co films, revealing spin-flop phenomena and complex hysteresis behaviors near the magnetic compensation temperature, providing insights for spintronic applications.

Contribution

It uncovers the influence of spin-flop transitions on the anomalous Hall effect and hysteresis loops in ferrimagnetic Hf/Gd-Fe-Co films near compensation temperatures.

Findings

Spin-flop occurs at ~0.6 T near $T_{comp}$ in sheet films.

Hysteresis loops differ between sheet and Hall bar devices.

Anomalous Hall resistance shows unusual temperature dependence under magnetic fields.

Abstract

Here we investigate the temperature dependence of anomalous Hall effect in Hf/GdFeCo/MgO sheet film and Hall bar device. The magnetic compensation temperature ($T_{comp}$) for the sheet film and device is found to be ~240 K and ~118 K, respectively. In sheet film, spin-flopping is witnessed at a considerably lower field, 0.6 T, close to $T_{comp}$. The AHE hysteresis loops in the sheet film have a single loop whereas in the Hall bar device, hystereses consist of triple loops are observed just above the Tcomp. Moreover, the temperature-dependent anomalous Hall resistance ($R_\mathrm{AHE}$) responds unusually when a perpendicular magnetic field is applied while recording the $R_\mathrm{AHE}$. The zero-field $R_\mathrm{AHE}$ scan suggests the Hall signal generates solely from the FeCo moment. However, the behavior of 3 T-field $R_\mathrm{AHE}$ scan in which the $R_\mathrm{AHE}$ drops close to zero near the $T_{comp}$ seems to be following the net magnetization response of the device, is explained by considering the low field spin-flopping around the compensation temperature. The results presented here give important insight to understand the complex AHE behavior of ferrimagnets for their spintronic applications.