Structural phase transitions in EuFe2As2 superconductor at low temperatures and high pressures

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Journal of Physics: Condensed Matter

DOI:https://doi.org/10.1088/0953-8984/23/36/365703· OSTI ID:1026752

Uhaya, Walter ^[1]; Tsoi, Georgiy ^[1]; Vohra, Y. K. ^[1]; McGuire, Michael A ^[2]; Safa-Sefat, Athena ^[2]

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1. University of Alabama, Birmingham
2. ORNL

The crystal structure of EuFe{sub 2}As{sub 2} has been studied up to a pressure of 35 GPa and down to a temperature of 8 K using temperature dependent x-ray diffraction in a diamond anvil cell at a synchrotron source. At 4.3 GPa, we have detected a structural phase transition from a high temperature tetragonal phase with I4/mmm space group to a low temperature orthorhombic phase with Fmmm space group around 120 K. With the application of pressure at a low temperature of 10 K, the orthorhombic phase is suppressed and a phase change to a collapsed tetragonal phase with I4/mmm space group is observed at 11 GPa. This collapsed tetragonal phase is similar to the one observed at ambient temperature and pressure above 8.5 GPa. We have shown that the collapsed tetragonal phase of EuFe{sub 2}As{sub 2} has the same pressure-volume (P-V) equation of state at ambient temperature and at 10 K, implying that the high pressure phase of EuFe{sub 2}As{sub 2} has a negligible thermal expansion coefficient.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1026752
• Journal Information: Journal of Physics: Condensed Matter, Journal Name: Journal of Physics: Condensed Matter Journal Issue: 36 Vol. 23; ISSN 0953-8984
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMBIENT TEMPERATURE
CRYSTAL STRUCTURE
DIAMONDS
SPACE GROUPS
SUPERCONDUCTORS
SYNCHROTRONS
THERMAL EXPANSION
X-RAY DIFFRACTION