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arXiv · 1210.3645

Simultaneous measurement of pressure evolution of crystal structure and superconductivity in FeSe0.92 using designer diamonds

Walter Uhoya·Georgiy Tsoi·Yogesh Vohra·Nathaniel Wolanyk·Sistla Muralidhara Rao·Maw-Kuen Wu·Samuel Weir
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Abstract

Simultaneous high pressure x-ray diffraction and electrical resistance measurements have been carried out on a PbO type α-FeSe0.92 compound to a pressure of 44 GPa and temperatures down to 4 K using designer diamond anvils at synchrotron source. At ambient temperature, a structural phase transition from a tetragonal (P4/nmm) phase to an orthorhombic (Pbnm) phase is observed at 11 GPa and the Pbnm phase persists up to 74 GPa. The superconducting transition temperature (TC) increases rapidly with pressure reaching a maximum of ~28 K at ~ 6 GPa and decreases at higher pressures, disappearing completely at 14.6 GPa. Simultaneous pressure-dependent x-ray diffraction and resistance measurements at low temperatures show superconductivity only in a low pressure orthorhombic (Cmma) phase of the α-FeSe0.92. Upon increasing pressure at 10 K near TC, crystalline phases change from a mixture of orthorhombic (Cmma) and hexagonal (P63/mmc) to a high pressure orthorhombic (Pbnm) phase near 6.4 GPa where TC is maximum.

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Walter Uhoya, Georgiy Tsoi, Yogesh Vohra, Nathaniel Wolanyk, Sistla Muralidhara Rao, Maw-Kuen Wu, Samuel Weir. 2012-10-12. Simultaneous measurement of pressure evolution of crystal structure and superconductivity in FeSe0.92 using designer diamonds. https://doi.org/10.1209/0295-5075%2F99%2F26002

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