Spin pumping into quantum spin chains

TL;DR

This paper explores how spin pumping into a quantum ferromagnetic spin chain described by a Tomonaga-Luttinger liquid reveals strong interaction effects through temperature and length dependence of Gilbert damping, with potential experimental realization in CsCuCl3.

Contribution

It introduces a theoretical framework for understanding spin pumping into strongly interacting quantum spin chains using the TL liquid model, highlighting the impact on ferromagnetic resonance.

Findings

Gilbert damping depends on temperature and junction length.

Strong interactions in the TL liquid influence ferromagnetic resonance.

CsCuCl3 identified as a candidate material for experimental realization.

Abstract

We theoretically investigate spin pumping into a quantum easy-plane ferromagnetic spin chain system. This quantum spin chain is effectively described by the Tomonaga-Luttinger (TL) liquid despite the ferromagnetic exchange interaction because of the easy-plane magnetic anisotropy. This TL liquid state has an extremely strong interaction that is hardly realized in other quantum antiferromagnetic chain systems or weakly interacting electron systems. We show how the strongly interacting TL liquid affects the ferromagnetic resonance that occurs in the ferromagnetic insulator. In particular, we discuss the dependence of the Gilbert damping on the temperature and the junction length. The Gilbert damping allows us to extract information about the above-mentioned strong interaction within the quantum ferromagnetic spin chain. We also point out that a well-known compound CsCuCl$_3$ will be suitable for the realization of our setup.