Year: 2017
Type: article
Abstract: To illustrate a simple mean-field-like approach for examining quantum phase transitions we consider the J – J ′ quantum Heisenberg antiferromagnet on a square lattice. The exchange couplings J and J ′ are competing with each other. The ratio J ′ / J is the control parameter and its change drives the transition. We adopt a variational ansatz, calculate the ground-state energy as well as the order parameter and describe the quantum phase transition inherent in the model. This description corresponds completely to the standard Landau theory of phase transitions. We also discuss how to generalize such an approach for more complicated quantum spin models.
Source: European Journal of Physics
Authors: Johannes Richter, Oleg Derzhko
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G3079381619, G742391978
OpenAlex ID: W2558223756