Observation of magnon torques mediated by orbital hybridization at the light metal/antiferromagnetic insulator interface

TL;DR

This study demonstrates highly efficient magnon torques at a Cr/NiO interface driven by orbital hybridization, enabling room-temperature magnetic switching with low power consumption, advancing spintronic technologies.

Contribution

It reveals that orbital hybridization at the interface significantly enhances magnon torque efficiency, surpassing conventional systems.

Findings

Effective spin Hall conductivity is twice that of conventional systems.

Room-temperature switching of CoFeB achieved with low power density.

Magnon torque originates from orbital hybridization and symmetry breaking.

Abstract

Magnon torques, which can operate without involving moving electrons, could circumvent the Joule heating issue. In conventional magnon torque systems, the spin source layer with strong spin-orbit coupling is utilized to inject magnons, and the efficiency is limited by the inherent spin Hall conductivity of the spin source layer. In this work, we observe magnon torques in the Cr/NiO/ferromagnet heterostructure with the effective spin Hall conductivity of 2.45x10^5 hbar/(2e{\Omega}m), twice that of the best conventional magnon torque system. We demonstrate the magnon-torque-driven switching of a perpendicularly magnetized CoFeB layer at room temperature, with a switching power consumption density of 0.136 mW/{\mu}m^2. We find that the magnon torque originates from the orbital hybridization and interfacial inversion symmetry breaking at the Cr/NiO interface. Our findings not only significantly enhance the efficiency of magnon torques, but also provide key insights into the fundamental mechanisms of magnon injections.