Magnetic glassy phase in FeSeTe single crystals

TL;DR

This study investigates the magnetic phase evolution in FeSeTe single crystals, revealing a transition from antiferromagnetic order to a glassy magnetic state with increasing selenium content, supported by experimental and computational evidence.

Contribution

It provides new insights into the coexistence and evolution of antiferromagnetic and glassy magnetic phases in FeSeTe crystals as a function of Se content.

Findings

Long-range AFM order diminishes with more Se

Glassy magnetic behavior appears and vanishes at high Se levels

Muon spectroscopy reveals local magnetic environments

Abstract

The evolution of the magnetic order in FeSeTe crystals as a function of Se content was investigated by means of ac/dc magnetometry and muon-spin spectroscopy. Experimental results and self-consistent DFT calculations both indicate that muons are implanted in vacant iron-excess sites, where they probe a local field mainly of dipolar origin, resulting from an antiferromagnetic (AFM) bicollinear arrangement of iron spins. This long-range AFM phase disorders progressively with increasing Se content. At the same time all the tested samples manifest a marked glassy character that vanishes for high Se contents. The presence of local electronic/compositional inhomogeneities most likely favours the growth of clusters whose magnetic moment "freezes" at low temperature. This glassy magnetic phase justifies both the coherent muon precession seen at short times in the asymmetry data, as well as the glassy behaviour evidenced by both dc and ac magnetometry.