Antiferromagnetic spin Seebeck effect across the spin-flop transition: A stochastic Ginzburg-Landau simulation

TL;DR

This study uses stochastic Ginzburg-Landau simulations to analyze how the antiferromagnetic spin Seebeck effect behaves across the spin-flop transition, revealing that sign reversal depends on interfacial coupling and spin dephasing.

Contribution

It demonstrates that the sign reversal of the spin Seebeck effect is controlled by microscopic interfacial exchange coupling and spin dephasing, not a universal property.

Findings

Sign reversal occurs when coupling to the staggered magnetization dominates.

No sign reversal when coupling to the net magnetization dominates.

Sign reversal is influenced by spin dephasing in the metal layer.

Abstract

We investigate the antiferromagnetic spin Seebeck effect across the spin-flop transition in a numerical simulation based on the time-dependent Ginzburg-Landau equation for a bilayer of a uniaxial insulating antiferromagnet and an adjacent metal. By directly simulating the rate of change of the conduction-electron spin density ${\bf s}$ in the adjacent metal layer, we demonstrate that a sign reversal of the antiferromagnetic spin Seebeck effect across the spin-flop transition occurs when the interfacial coupling of ${\bf s}$ to the staggered magnetization ${\bf n}$ of the antiferromagnet dominates, whereas no sign reversal appears when the interfacial coupling of ${\bf s}$ to the magnetization ${\bf m}$ dominates. Moreover, we show that the sign reversal is influenced by the degree of spin dephasing in the metal layer. Our result indicates that the sign reversal is not a generic property of a simple uniaxial antiferromagnet, but controlled by microscopic details of the exchange coupling at the interface and the spin dephasing in the metal layer.