Impact of the crystal orientation on spin-orbit torques in Fe/Pd bilayers

TL;DR

This study investigates how crystal orientation affects spin-orbit torque efficiency in Fe/Pd bilayers, revealing that epitaxial structures exhibit higher damping-like torque efficiency than polycrystalline ones, with implications for spin-logic device design.

Contribution

It provides new insights into the influence of crystal orientation on spin-orbit torques in Fe/Pd heterostructures, highlighting the importance of epitaxial quality.

Findings

Epitaxial bilayers show higher damping-like torque efficiency than polycrystalline ones.

Field-like torque is negligible across all bilayer structures.

Damping-like torque decreases as epitaxial quality deteriorates.

Abstract

Spin-orbit torques in ferromagnetic (FM)/non-magnetic (NM) heterostructures offer more energy-efficient means to realize spin-logic devices; however, their strengths are determined by the heterostructure interface. This work examines crystal orientation impact on the spin-orbit torque efficiency in different Fe/Pd bilayer systems. Spin torque ferromagnetic measurements evidence that the damping-like torque efficiency is higher in epitaxial than in polycrystalline bilayer structures while the field-like torque is negligible in all bilayer structures. The strength of the damping-like torque decreases with deterioration of the bilayer epitaxial quality. The present finding provides fresh insight for the enhancement of spin-orbit torques in magnetic heterostructures.