Quantum-Mechanically Induced Asymmetry in the Phase Diagrams of Spin-Glass Systems

C. Nadir Kaplan; A. Nihat Berker

doi:10.1103/physrevlett.100.027204

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arXiv · 0709.3589

Quantum-Mechanically Induced Asymmetry in the Phase Diagrams of Spin-Glass Systems

C. Nadir Kaplan·A. Nihat Berker

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Abstract

The spin-1/2 quantum Heisenberg model is studied in all spatial dimensions d by renormalization-group theory. Strongly asymmetric phase diagrams in temperature and antiferromagnetic bond probability p are obtained in dimensions d \geq 3. The asymmetry at high temperatures approaching the pure ferromagnetic and antiferromagnetic systems disappears as d is increased. However, the asymmetry at low but finite temperatures remains in all dimensions, with the antiferromagnetic phase receding to the ferromagnetic phase. A finite-temperature second-order phase boundary directly between the ferromagnetic and antiferromagnetic phases occurs in d \geq 6, resulting in a new multicritical point at its meeting with the boundaries to the paramagnetic phase. In d=3,4,5, a paramagnetic phase reaching zero temperature intervenes asymmetrically between the ferromagnetic and reentrant antiferromagnetic phases. There is no spin-glass phase in any dimension.

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C. Nadir Kaplan, A. Nihat Berker. 2008-04-09. Quantum-Mechanically Induced Asymmetry in the Phase Diagrams of Spin-Glass Systems. https://doi.org/10.1103/physrevlett.100.027204

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