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Journal of Physics: Conference Series 1274, 012012 (2019)

ISSN: 1742-6596

Fermionized Heisenberg model on a non-Bravais lattice with exact local constraint: Application to a honeycomb lattice

Pham Thi Thanh Nga, Nguyen Toan Thang

We study magnetic order of the Heisenberg model on a non-Bravais lattice based on the Popov-Fedotov trick for exactly treating the local constraint on on-site spin number. The spin operators are represented by auxiliary fermions and an imaginary chemical potential is introduced. The following steps are sketched: i) Parameterizing classical ground state by a magnetic ordering vector and angles between the spins within a unit cell. ii) Going to a local coordinate system. ii) Using functional integral representation with Hubbard-Stratonovich for partition function and calculating determinants of block matrices by Silvester-Powel method. For illustration we obtain some explicit expressions for ferromagnetic Heisenberg model on a honeycomb lattice and compare them with the slave boson results.

DOI: 10.1088/1742-6596/1274/1/012012

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