Pressure-induced lattice collapse in the tetragonal phase of single-crystalline Fe_1.05Te

Pressure-induced lattice collapse was discovered in tetragonal (T) phase of single crystal Fe1.05Te at room temperature through x-ray and neutron-diffraction measurements. A remarkable compression along the c axis (similar to 5%) was observed upon increasing pressure from the ambient condition to 4 GPa. Indexed results demonstrate that the crystallographic structure remains unchanged after the collapse, revealing that the collapse does not break symmetry of crystal structure. The Fe-spin state change was proposed to account for the lattice collapse. The equations of state for the T phase and pressure-induced collapsed T phase were determined from the diffraction measurements.