N\'eel temperature and reentrant H-T phase diagram of quasi-2D frustrated magnets

TL;DR

This paper explores the relationship between Ne9el temperature and frustration in quasi-2D quantum magnets, analyzing how these quantities vary with frustration parameters and magnetic field, with implications for understanding magnetic frustration.

Contribution

It provides a detailed analysis of the Ne9el temperature and frustration ratio in the J1-J2 model using the Tyablikov approach, including field dependence and reentrant behavior.

Findings

The Ne9el temperature depends on the frustration parameter J2/J1.

The empirical frustration ratio can reliably indicate frustration strength under certain conditions.

Reentrant magnetic behavior due to quantum fluctuations is identified.

Abstract

In quasi-2D quantum magnets the ratio of N\'eel temperature $T_\text N$ to Curie-Weiss temperature $\Theta_\text{CW}$ is frequently used as an empirical criterion to judge the strength of frustration. In this work we investigate how these quantities are related in the canonical quasi-2D frustrated square or triangular $J_1$-$J_2$ model. Using the self-consistent Tyablikov approach for calculating $T_\text N$ we show their dependence on the frustration control parameter $J_2/J_1$ in the whole N\'eel and columnar antiferromagnetic phase region. We also discuss approximate analytical results. In addition the field dependence of $T_\text N(H)$ and the associated possible reentrance behavior of the ordered moment due to quantum fluctuations is investigated. These results are directly applicable to a class of quasi-2D oxovanadate antiferromagnets. We give clear criteria to judge under which conditions the empirical frustration ratio $f=\Theta_\text{CW}/T_\text N$ may be used as measure of frustration strength in the quasi-2D quantum magnets.