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arXiv · 1712.06282

Néel temperature and reentrant H-T phase diagram of quasi-2D frustrated magnets

Burkhard Schmidt·Peter Thalmeier
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Abstract

In quasi-2D quantum magnets the ratio of Néel temperature $T_\text N$ to Curie-Weiss temperature $Θ_\text{CW}$ 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 Néel 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 $f=Θ_\text{CW}/T_\text N$ may be used as measure of frustration strength in the quasi-2D quantum magnets.

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Burkhard Schmidt, Peter Thalmeier. 2017-12-18. Néel temperature and reentrant H-T phase diagram of quasi-2D frustrated magnets. https://doi.org/10.1103/physrevb.96.214443

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