Solitonic Spin-Liquid State Due to the Violation of the Lifshitz Condition in Fe(1+y)Te

Phys Rev Lett. 2015 Oct 23;115(17):177203. doi: 10.1103/PhysRevLett.115.177203. Epub 2015 Oct 21.

Abstract

A combination of phenomenological analysis and Mössbauer spectroscopy experiments on the tetragonal Fe(1+y)Te system indicates that the magnetic ordering transition in compounds with higher Fe excess, y≥0.11, is unconventional. Experimentally, a liquidlike magnetic precursor with quasistatic spin order is found from significantly broadened Mössbauer spectra at temperatures above the antiferromagnetic transition. The incommensurate spin-density wave order in Fe(1+y)Te is described by a magnetic free energy that violates the weak Lifshitz condition in the Landau theory of second-order transitions. The presence of multiple Lifshitz invariants provides the mechanism to create multidimensional, twisted, and modulated solitonic phases.