Spin Hall Effect Induced Spin Transfer Through an Insulator

Abstract

When charge current passes through a normal metal that exhibits spin Hall effect, spin accumulates at the edge of the sample in the transverse direction. We predict that this spin accumulation, or spin voltage, enables quantum tunneling of spin through an insulator or vacuum to reach a ferromagnet without transferring charge. In a normal metal/insulator/ferromagnetic insulator trilayer (such as Pt/oxide/YIG), the quantum tunneling explains the spin-transfer torque and spin pumping that exponentially decay with the thickness of the insulator. In a normal metal/insulator/ferromagnetic metal trilayer (such as Pt/oxide/Co), the spin transfer in general does not decay monotonically with the thickness of the insulator. Combining with the spin Hall magnetoresistance, this tunneling mechanism points to the possibility of a new type of tunneling spectroscopy that can probe the magnon density of states of a ferromagnetic insulator in an all-electrical and noninvasive manner.

9 pages, 3 figures

References in corpus (4)

• Theory of spin Hall magnetoresistance
• Unidirectional spin Hall magnetoresistance in ferromagnet/normal metal bilayers
• Dissipationless Multiferroic Magnonics
• Minimal Model of Spin-Transfer Torque and Spin Pumping caused by Spin Hall Effect

Cited by in corpus (5)

• Pure spin currents in magnetically ordered insulator/normal metal heterostructures
• Current direction anisotropy of the spin Hall magnetoresistance in nickel ferrite thin films with bulk-like magnetic properties
• Edelstein and inverse Edelstein effects caused by the pristine surface states of topological insulators
• Theory of in-plane current induced spin torque in metal/ferromagnet bilayers
• Effect of Quantum Tunneling on Spin Hall Magnetoresistance