Evidence for a magnetic field-induced unconventional nematic state in the frustrated and anisotropic spin-chain cuprate LiCuSbO$_4$

TL;DR

This paper provides experimental evidence for a magnetic field-induced nematic state in the frustrated spin-chain cuprate LiCuSbO$_4$, supported by NMR, magnetization, ESR data, and theoretical DMRG modeling.

Contribution

It reports the first experimental observation of a magnetic field-induced nematic state in LiCuSbO$_4$, supported by combined experimental and theoretical analysis.

Findings

Observation of a field-induced spin gap above 13 T

Field-dependent power-law behavior of NMR relaxation rate

Theoretical support from DMRG modeling of frustrated spin chains

Abstract

Modern theories of quantum magnetism predict exotic multipolar states in weakly interacting strongly frustrated spin-1/2 Heisenberg chains with ferromagnetic nearest neighbor (NN) inchain exchange in high magnetic fields. Experimentally these states remained elusive so far. Here we report the evidence for a long-sought magnetic field-induced nematic state arising above a field of $\sim 13$ T in the edge-sharing chain cuprate LiSbCuO$_4$ $\equiv$ LiCuSbO$_4$. This interpretation is based on the observation of a field induced spin-gap in the measurements of the $^7$Li NMR spin relaxation rate $T_1^{-1}$ as well as a contrasting field-dependent power-law behavior of $T_1^{-1}$ vs. $T$ and is further supported by static magnetization and ESR data. An underlying theoretical microscopic approach favoring a nematic scenario is based essentially on the NN XYZ exchange anisotropy within a model for frustrated spin-1/2 chains. It is investigated by the DMRG technique. The employed exchange parameters are justified qualitatively by electronic structure calculations for LiCuSbO$_4$.