Phenomenological theory of spinor Bose-Einstein condensates

TL;DR

This paper develops a phenomenological model for spinor Bose-Einstein condensates, exploring spontaneous magnetization and phase diagrams, and discusses experimental verification of Bose-Einstein ferromagnetism.

Contribution

It introduces a new phenomenological framework for understanding spinor BECs, including effects of hyperfine interactions and extended Gross-Pitaevskii equations.

Findings

Bose-Einstein condensation can induce spontaneous magnetization without hyperfine interactions.

The phase diagram of spinor condensates is mapped considering hyperfine interactions.

Potential experimental methods for observing Bose-Einstein ferromagnetism are proposed.

Abstract

A phenomenological model is proposed to describe the behavior of spinor Bose-Einstein condensates. In the absence of hyperfine spin-spin interactions, Bose-Einstein condensation leads to a spontaneous magnetization at the same transition temperature. This is the so-called Bose-Einstein ferromagnetism. Including the hyperfine spin interactions, the phase diagram of the spinor condensate in an optical trap is studied and the Gross-Pitaevskii equation is extended. The possibility of checking for the existence of the Bose-Einstein ferromagnetism experimentally is also discussed.