Rb-NMR study of the quasi-one dimensional competing spin-chain compound Rb2Cu2Mo3O12

TL;DR

This study uses Rb-NMR to investigate the magnetic properties of the quasi-one dimensional spin chain compound Rb2Cu2Mo3O12, revealing a field-induced transition from gapped to gapless states and analyzing its quantum critical behavior.

Contribution

It provides the first detailed NMR analysis of Rb2Cu2Mo3O12, demonstrating field-induced quantum phase transition and characterizing the Luttinger parameter in a spin nematic TLL state.

Findings

Transition from gapped to gapless state at H_C ≈ 2 T

Magnetic order observed below 1 K in the gapless phase

Power-law temperature dependence of 1/T_1 and field-dependent Luttinger parameter K

Abstract

Rb-NMR study has been performed on the quasi-one dimensional competing spin chain Rb2Cu2Mo3O12 with ferromagnetic and antiferromagnetic exchange interactions on nearest neighboring and next nearest neighboring spins, respectively. The system changes from a gapped ground state at zero field to the gapless state at H_C \simeq 2 T, where the existence of magnetic order below 1 K was demonstrated by a broadening of NMR spectrum, associated with a critical divergence of 1/T_1. In higher temperature region, 1/T_1 showed a power-law type temperature dependence, from which the field dependence of Luttinger parameter K was obtained and compared with theoretical calculations based on the spin nematic Tomonaga Luttinger Liquid (TLL) state.