Poisson-Dirichlet distributions and weakly first-order spin-nematic phase transitions

RWTH Publications (RWTH Aachen)

Abstract

We provide a quantitative characterization of generic weakly first-order thermal phase transitions out of planar spin-nematic states in three-dimensional spin-one quantum magnets, based on calculations using Poisson-Dirichlet distributions (PD) within a universal loop model formulation, combined with large-scale quantum Monte Carlo calculations. In contrast to earlier claims, the thermal melting of the nematic state is not continuous, instead a weakly first-order transition is identified from both thermal properties and the distribution of the nematic order parameter. Furthermore, based on PD calculations, we obtain exact results for the order parameter distribution and Binder cumulants at the discontinuous melting transition. Our findings establish the thermal melting of planar spin-nematic states as a generic platform for quantitative approaches to weakly first-order phase transitions in quantum systems with a continuous SU(2) internal symmetry.

Authors 4

1. Nils Caci Aachen Institute for Theoretical Solid State Physics

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Solid State Physics , JARA FIT and JARA CSD , RWTH Aachen University , 52056 Aachen , Germany

2. Peter Mühlbacher

   University of Warwick

   Affiliation as printed

   Department of Mathematics , University of Warwick , Coventry CV4 7AL , United Kingdom

3. Daniel Ueltschi

   University of Warwick

   Affiliation as printed

   Department of Mathematics , University of Warwick , Coventry CV4 7AL , United Kingdom

4. Stefan Weßel Aachen Institute for Theoretical Solid State Physics

   Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Solid State Physics , JARA FIT and JARA CSD , RWTH Aachen University , 52056 Aachen , Germany