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

TL;DR

This study investigates how temperature and crystallographic orientation influence the anisotropic magnetoresistance in epitaxial Fe65Co35 thin films, revealing orientation-dependent AMR ratios and magnetic anisotropy constants relevant for sensor design.

Contribution

It provides new insights into the orientation and temperature dependence of AMR and magnetic anisotropy in Fe65Co35 thin films, aiding the design of tunable magnetic sensors.

Findings

AMR ratio varies with crystallographic direction and temperature.

Fitted anisotropy constants confirm changes in magnetic properties.

AMR can be tailored for sensor applications.

Abstract

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.