Spin-Hall magnetoresistance and spin Seebeck effect in spin-spiral and paramagnetic phases of multiferroic CoCr2O4 films

TL;DR

This study investigates spin-Hall magnetoresistance and spin Seebeck effects in multiferroic CoCr2O4 films, revealing enhanced spin transport signals in non-collinear magnetic phases and their sensitivity to magnetic states.

Contribution

It demonstrates that spin transport signals are significantly enhanced in spin-spiral and spin lock-in phases of CoCr2O4, highlighting the influence of magnetic phases on interface spin interactions.

Findings

Enhanced SMR and SSE signals below spin-spiral and lock-in transitions.

Signals are an order of magnitude larger than at the ferrimagnetic transition.

Spin transport is sensitive to magnetic phases but not solely determined by bulk magnetization.

Abstract

We report on the spin-Hall magnetoresistance (SMR) and spin Seebeck effect (SSE) in multiferroic CoCr2O4 (CCO) spinel thin films with Pt contacts. We observe a large enhancement of both signals below the spin-spiral (Ts = 28 K) and the spin lock-in transitions (T_{lock_in} = 14 K). The SMR and SSE response in the spin lock-in phase are one order of magnitude larger than those observed at the ferrimagnetic transition temperature (Tc = 94 K), which indicates that the interaction between spins at the Pt|CCO interface is more efficient in the non-collinear magnetic state below Ts and T_{lock-in}. At T > Tc, magnetic field-induced SMR and SSE signals are observed, which can be explained by a high interface susceptibility. Our results show that the spin transport at the Pt|CCO interface is sensitive to the magnetic phases but cannot be explained solely by the bulk magnetization.