Universal scaling at field-induced magnetic phase transitions

TL;DR

This paper investigates the universal critical behavior of field-induced magnetic phase transitions in cubic dimer systems, demonstrating that the critical exponents align with Bose-Einstein condensation predictions across different coupling ratios.

Contribution

It provides the first comprehensive analysis showing the independence of critical exponents from interdimer coupling ratios in cubic dimer systems, confirming the universality class of the transition.

Findings

Critical exponents are independent of interdimer coupling ratios.

Exponents converge to the Bose-Einstein condensation value of 1.5.

Results explain the variability of exponents observed in experiments.

Abstract

We study field-induced magnetic order in cubic lattices of dimers with antiferromagnetic Heisenberg interactions. The thermal critical exponents at the quantum phase transition from a spin liquid to a magnetically ordered phase are determined from Stochastic Series Expansion Quantum Monte Carlo simulations. These exponents are independent of the interdimer coupling ratios, and converge to the value obtained by considering the transition as a Bose-Einstein condensation of magnons, alpha_(BEC) = 1.5. The scaling results are of direct relevance to the spin-dimer systems TlCuCl_3 and KCuCl_3, and explain the broad range of exponents reported for field-induced ordering transitions.