Title

Nonmonotonic Field Dependence Of The Neel Temperature In The Quasi-Two-Dimensional Magnet [Cu(Hf2)(Pyz)(2)]Bf4

Document Type

Article

Publication Date

2-1-2009

Abstract

The measured thermodynamic phase diagram of the quasi-two-dimensional magnet [Cu(HF2)(pyz)(2)]BF4(pyz=pyrazine=N2C4H4) exhibits an unusual nonmonotonic dependence of the Neel temperature T-N as a function of magnetic field H. The nonmonotonic behavior of T-N(H) results from two competing effects induced by the field: while H suppresses the amplitude of the order parameter by polarizing the spins along a given direction, it also reduces the phase fluctuations by changing the order parameter space from the sphere S-2 to the circle S-1. The latter effect dominates at low fields only if the system is close enough to its lower critical dimension (d(c)=2), i.e., when fluctuations become important. Our theoretical results reproduce the measured phase diagram and demonstrate that this unusual effect is realized in [Cu(HF2)(pyz)(2)]BF4.

Original Publication Title

Physical Review B

Volume

79

Issue

6

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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