Magnetic–crystallographic p,T‐phase diagram of Fe_1.141Te: A high‐pressure neutron diffraction study

Abstract

The crystal and magnetic structures of Fe1.141Te have been studied by neutron powder diffraction in the temperature range from 5 to 106 K and pressures in the range from ambient to ≈2.7 GPa. The p,T‐phase diagram contains three phases with monoclinic, orthorhombic, and tetragonal symmetry. The monoclinic phase was found to be stable for T ≲ 57 K and p < 0.4 GPa while the orthorhombic phase is stable for T ≲ 63 K and 0.4 ≲ p ≲ 2.16 GPa. The tetragonal phase is stable at high temperatures and becomes stable down to the lowest measured temperatures for p > 2.16 GPa. The monoclinic phase shows commensurate bicollinear antiferromagnetic order with propagation vector k = (½ 0 ½), while the orthorhombic phase is incommensurately antiferromagnetically ordered with propagation vector k = (½‐δ 0 ½). The δ−parameter increases linearly with the pressure for 0.4 ≲ p ≲ 2.16 GPa. Pressure‐induced ferromagnetic order was observed in the tetragonal phase for p ≳ 2.1 GPa and temperatures less than ∼68 K, depending on the pressure.

Pressure-Induced Ferromagnetism due to an Anisotropic Electronic Topological Transition inFe1.08Te

“…However, this does not affect the relative changes between different pressures. Our finding is further supported by neutron diffraction data on Fe 1.141 Te, which indicate that all Fe moments are oriented along the c-axis in the pressureinduced FM phase [30]. The saturated high-field magnetization increases with increasing pressure, signifying a stabilization of ferromagnetism under pressure.…”

“…Similarly, applying pressure on a sample drives the system through a series of phase transitions that closely resemble those induced by excess Fe content [24]. One such transition, being completely unanticipated, is of particular interest: a pressure-induced FM phase transition at low temper-atures [25,[30][31][32][33]. This phase has not been observed at ambient pressure for samples of any level of Fe excess.…”