Volume 99, Number 2, July 2012
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||24 July 2012|
Simultaneous measurement of pressure evolution of crystal structure and superconductivity in FeSe0.92 using designer diamonds
1 Department of Physics, University of Alabama at Birmingham (UAB) - Birmingham, AL 35294, USA (Presen address)
2 Illinois Wesleyan University (IWU) - Bloomington, IL 61702-2900, USA
3 Institute of Physics, Academia Sinica - Nankang, Taipei 115, Taiwan
4 Mail Stop L-041, Lawrence Livermore National Laboratory (LLNL) - Livermore, CA 94550, USA
Received: 4 May 2012
Accepted: 22 June 2012
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) phases to a high-pressure orthorhombic (Pbnm) phase near 6.4 GPa where TC is maximum.
PACS: 62.50.-p – High-pressure effects in solids and liquids / 74.62.Fj – Effects of pressure / 61.50.Ks – Crystallographic aspects of phase transformations; pressure effects
© EPLA, 2012
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