Eur. Phys. J. B 5, 735-743 (1998)
https://doi.org/10.1007/s100510050497

First and second order transition in frustrated XY systems^*

Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany

Corresponding authors: ^a Loison@physik.fu-berlin.de - ^b Schotte@physik.fu-berlin.de

Received: 18 February 1998
Revised: 24 April 1998
Accepted: 30 April 1998
Published online: 15 October 1998

Abstract

The nature of the phase transition for the XY stacked triangular antiferromagnet (STA) is a controversial subject at present. The field theoretical renormalization group (RG) in three dimensions predicts a first order transition. This prediction disagrees with Monte-Carlo (MC) simulations which favor a new universality class or a tricritical transition. We simulate by the Monte-Carlo method two models derived from the STA by imposing the constraint of local rigidity which should have the same critical behavior as the original model. A strong first order transition is found. Following Zumbach we analyze the second order transition observed in MC studies as due to a fixed point in the complex plane. We review the experimental results in order to clarify the critical behavior observed.