Strain-driven magnetic anisotropy and spin reorientation in epitaxial Co V 2 O 4 spinel oxide thin films

TL;DR

This study demonstrates how epitaxial strain in CoV2O4 thin films can control magnetic anisotropy and induce spin reorientation, revealing strong spin-lattice coupling and potential for spintronic applications.

Contribution

It provides a detailed experimental investigation of strain-induced magnetic anisotropy switching in epitaxial CoV2O4 thin films, highlighting their tunable magnetic properties.

Findings

Strain induces magnetic anisotropy switching in CoV2O4 films.

Compressive and tensile strains alter magnetic easy axes at different temperatures.

Strain reduces charge transport, increasing resistivity.

Abstract

CoV___O___ (CVO) stands out among spinel vanadates for its ultra-short V-V distances, placing it at the brink of itinerant electron behaviour-an ideal playground for strain engineering. In this work, we exploit this sensitivity by growing high-quality epitaxial CVO thin films on SrTiO___ (001) and MgO (001), inducing compressive and tensile strain, respectively. Using pulsed laser deposition under ultra-low oxygen pressure, we achieve high crystalline quality and straincontrolled tetragonal distortions: c > a under compression (STO) and c < a under tension (MgO). Resonant elastic X-ray scattering confirms a normal spinel structure, with cobalt occupying tetrahedral sites and vanadium octahedral ones. Both strain types reduce charge transport, driving the system into a highly resistive state. Magnetic measurements reveal strain-driven anisotropy switching: STO films transition from out-of-plane to in-plane easy axis below 90 K, while MgO films flip from in-plane to out-of-plane below 45 K. These results highlight CVO's exceptional responsiveness to lattice strain, unlocking a path to finely tunable electronic and magnetic properties. With its strong spin-lattice coupling and potential in spin Hall magnetoresistance, strained CVO emerges as a compelling platform for next-generation lowpower spintronic devices.