Controlling Luttinger liquid physics in spin ladders under a magnetic field

TL;DR

This study uses nuclear magnetic resonance to explore how magnetic fields influence Luttinger liquid behavior in spin ladders, revealing controllable parameters and phase transitions in a well-characterized model system.

Contribution

It demonstrates the ability to control Luttinger liquid parameters in spin ladders using magnetic fields and tests the Luttinger liquid model comprehensively.

Findings

Magnetic field dependence of 1/T_1 explained by Luttinger liquid theory

Observation of a phase transition to 3D order below 110 mK

BPCB as a model system for studying controllable Luttinger liquids

Abstract

We present a 14N nuclear magnetic resonance study of a single crystal of CuBr4(C5H12N)2 (BPCB) consisting of weakly coupled spin-1/2 Heisenberg antiferromagnetic ladders. Treating ladders in the gapless phase as Luttinger liquids, we are able to fully account for (i) the magnetic field dependence of the nuclear spin-lattice relaxation rate 1/T_1 at 250 mK and for (ii) the phase transition to a 3D ordered phase occuring below 110 mK due to weak interladder exchange coupling. BPCB is thus an excellent model system where the possibility to control Luttinger liquid parameters in a continuous manner is demonstrated and Luttinger liquid model tested in detail over the whole fermion band.