Critical scales in anisotropic spin systems from functional renormalization

Autor(en)

Stefan Göttel, Sabine Andergassen, Carsten Honerkamp, Dirk Schuricht, Stefan Wessel

Abstrakt

We apply a recently developed functional renormalization group (FRG) scheme for quantum spin systems to the spin-1/2 antiferromagnetic XXZ model on a two-dimensional square lattice. Based on an auxiliary fermion representation we derive flow equations which allow a resummation of the perturbation series in the spin-spin interactions. Spin susceptibilities are calculated for different values of the anisotropy parameter. The phase transition between planar and axial ordering at the isotropic point is reproduced correctly. The results for the critical scales from the FRG as quantitative measures for the ordering temperatures are in good agreement with the exact solution only in the Ising limit. In particular on the easy-plane side, the deviations from critical temperatures obtained with quantum Monte Carlo are rather large. Furthermore, at the isotropic point the Mermin-Wagner theorem is violated such that a description of the critical behavior and an extraction of scaling exponents is not possible. We discuss possible reasons for these discrepancies.

Organisation(en)

Quantenoptik, Quantennanophysik und Quanteninformation

Externe Organisation(en)

Rheinisch-Westfälische Technische Hochschule Aachen

Journal

Physical Review B

Band

85

Anzahl der Seiten

8

ISSN

1098-0121

DOI

https://doi.org/10.1103/PhysRevB.85.214406

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

103026 Quantenoptik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/bd0af697-3dee-4f46-b569-37f0fe18cf83