Field-induced transverse spin ordering in FeBr2

TL;DR

This paper investigates the weak first-order phase transitions and spin ordering phenomena in FeBr2 under transverse magnetic fields, revealing the role of non-diagonal coupling and symmetry-breaking effects.

Contribution

It provides new experimental evidence of field-induced transverse spin ordering and clarifies the nature of phase transitions in FeBr2.

Findings

Identification of weak first-order phase transitions in FeBr2

Evidence of in-plane moment ordering due to non-diagonal coupling

Discontinuous increase of order parameters under transverse fields

Abstract

Weak first-order phase transitions from axial to oblique spin ordering in FeBr2 are evidenced by SQUID magnetometry in axial fields H1(T) above the multicritical point, Hm = 2.4 MA/m, Tm = 4.6 K, and below the antiferro-to-paramagnetic phase line, Hc(T), in agreement with recent specific heat data (Aruga Katori et al., 1996). The ordering of the in-plane moments is probably due to non-diagonal coupling to the longitudinal ones, both of which increase dis-continuously at H1(T) only under an additional symmetry-breaking transverse field.