Eur. Phys. J. B (2015) 88: 119
https://doi.org/10.1140/epjb/e2015-50713-6

Regular Article

Pressure-induced successive magnetic and structural phase transitions in Fe_1.087Te

¹ Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
² Institute Max von Laue-Paul Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France

^a e-mail: jenserik@chem.au.dk

Received: 14 October 2014
Received in final form: 24 January 2015
Published online: 11 May 2015

Abstract

The crystal and magnetic structures of Fe_1.087Te have been studied by neutron powder diffraction in the temperature range from 5 to 170 K at pressures in the range from ≈0.8 to ≈7 GPa. The p,T-phase diagram contains three phases with monoclinic, orthorhombic and tetragonal symmetry. The monoclinic and orthorhombic phases are both antiferromagnetically ordered and stable at temperatures below ≈69 K while the non-magnetic tetragonal phase is stable above this temperature. The monoclinic phase is stable for p ≲ 1.2 GPa while the orthorhombic phase is stable for 1.2 ≲ p ≲ 1.7 GPa and the tetragonal phase becomes stable at higher pressures at the lowest measured temperatures. The magnetic ordering is antiferromagnetic bicollinear and commensurate in the monoclinic phase but incommensurate and pressure dependent in the orthorhombic phase. The pressure-induced collapse of magnetic order at ≈1.7 GPa is accompanied by abrupt changes in volume and compressibility, suggestive of a spin state change of the Fe²⁺ ions in the FeTe layers.