Dynamic generation of spin spirals of moir\'e trapped carriers via exciton mediated spin interactions

TL;DR

This paper demonstrates how exciton-mediated spin interactions in moiré superlattices of TMD bilayers can generate and control spin spiral magnetic orders, revealing new pathways for spintronic applications.

Contribution

It introduces a novel mechanism where long-lived interlayer excitons mediate controllable Heisenberg and Dzyaloshinskii-Moriya interactions in moiré trapped carriers.

Findings

Strong Heisenberg spin interactions observed.

Long-range Dzyaloshinskii-Moriya interactions demonstrated.

Control of spin spiral direction via exciton current achieved.

Abstract

Stacking transition metal dichalcogenides (TMDs) to form moir\'e superlattices has provided exciting opportunities to explore many-body correlation phenomena of the moir\'e trapped carriers. TMDs bilayers, on the other hand, host long-lived interlayer exciton (IX), an elementary excitation of long spin-valley lifetime that can be optically or electrically injected. Here we find that, through the Coulomb exchange between mobile IXs and carriers, the IX bath can mediate both Heisenberg and Dzyaloshinskii-Moriya type spin interactions between moir\'e trapped carriers, controllable by exciton density and exciton spin current respectively. We show the strong Heisenberg interaction, and the extraordinarily long-ranged Dzyaloshinskii-Moriya interaction here can jointly establish robust spin spiral magnetic orders in Mott-Wigner crystal states at various filling factors, with spiral direction controlled by exciton current.