Symmetry-driven Intrinsic Nonlinear Pure Spin Hall Effect

TL;DR

This paper introduces the intrinsic nonlinear pure spin Hall effect (NPSHE), demonstrating its quantum geometric origin, symmetry conditions, and potential for room-temperature spintronic applications.

Contribution

It identifies symmetry conditions for NPSHE, analyzes its quantum geometric origin, and predicts significant effects in specific materials for spintronic device development.

Findings

39 magnetic point groups support NPSHE

Significant nonlinear spin currents predicted in Kramers-Weyl metals

Room-temperature NPSHE effects position materials for spin-torque devices

Abstract

The generation of pure spin current, spin angular momentum transport without charge flow, is crucial for developing energy-efficient spintronic devices with minimal Joule heating. Here, we introduce the intrinsic nonlinear pure spin Hall effect (NPSHE), where both linear and second-order charge Hall currents vanish. We show intrinsic second-order spin angular momentum transport in metals and insulators through a detailed analysis of the quantum geometric origin of different spin current contributions. Our comprehensive symmetry analysis identifies 39 magnetic point groups that support NPSHE, providing a foundation for material design and experimental realization. We predict significant nonlinear pure spin Hall currents in Kramers-Weyl metals even at room temperature, positioning them as potential candidates for NPSHE-based spin-torque devices. Our work lays a practical pathway for realizing charge-free angular momentum transport for the development of next-generation, energy-efficient spintronic devices.