Quantum-critical spin dynamics in a Tomonaga-Luttinger liquid studied with muon-spin relaxation

TL;DR

This study demonstrates that muon-spin relaxation can effectively probe quantum-critical spin dynamics in a Tomonaga-Luttinger liquid, providing a new method to analyze low-dimensional quantum magnetic systems.

Contribution

It introduces muon-spin relaxation as a tool to study quantum-critical spin dynamics in high magnetic fields within a Tomonaga-Luttinger liquid, highlighting its advantages over neutron scattering.

Findings

Finite-temperature scaling of muon relaxation rate observed

Luttinger parameter K determined from relaxation data

Comparison of local probe benefits and limitations

Abstract

We demonstrate that quantum-critical spin dynamics can be probed in high magnetic fields using muon-spin relaxation ($\mu^{+}$SR). Our model system is the strong-leg spin ladder bis(2,3-dimethylpyridinium) tetrabromocuprate (DIMPY). In the gapless Tomonaga-Luttinger liquid phase we observe finite-temperature scaling of the $\mu^{+}$SR $1/T_1$ relaxation rate which allows us to determine the Luttinger parameter $K$. We discuss the benefits and limitations of local probes compared with inelastic neutron scattering.