Observation of Nonlinear Spin-Charge Conversion in the Thin Film of Nominally Centrosymmetric Dirac Semimetal SrIrO3 at Room Temperature

TL;DR

This study demonstrates nonlinear spin-charge conversion at room temperature in SrIrO3 thin films by breaking inversion symmetry at the interface, revealing a new pathway for spintronics applications in centrosymmetric materials.

Contribution

It reports the first observation of nonlinear spin-charge conversion in a nominally centrosymmetric Dirac semimetal, enabled by interface-induced inversion symmetry breaking.

Findings

Large second-order magnetoelectric coefficient observed at room temperature

Nonlinear charge-spin conversion driven by antisymmetric spin-orbit interaction

Interface symmetry breaking induces spin splitting in Dirac semimetal bands

Abstract

Spin-charge conversion via spin-orbit interaction is one of the core concepts in the current spintronics research. The efficiency of the interconversion between charge and spin current is estimated based on Berry curvature of Bloch wavefunction in the linear-response regime. Beyond the linear regime, nonlinear spin-charge conversion in the higher-order electric field terms has recently been demonstrated in noncentrosymmetric materials with nontrivial spin texture in the momentum space. Here we report the observation of the nonlinear charge-spin conversion in a nominally centrosymmetric oxide material, SrIrO3, by breaking inversion symmetry at the interface. A large second-order magnetoelectric coefficient is observed at room temperature because of the antisymmetric spin-orbit interaction at the interface of Dirac semimetallic bands, which is subject to the symmetry constraint of the substrates. Our study suggests that nonlinear spin-charge conversion can be induced in many materials with strong spin-orbit interaction at the interface by breaking the local inversion symmetry to give rise to spin splitting in otherwise spin degenerate systems.