title: Anomalous compressibility effects and superconductivity of EuFe2As2 under high pressures.
abstract: The crystal structure and electrical resistance of structurally layered EuFe(2)As(2) have been studied up to 70 GPa and down to a temperature of 10 K, using a synchrotron x-ray source and designer diamond anvils. The room temperature compression of the tetragonal phase of EuFe(2)As(2) (I4/mmm) results in an increase in the a-axis length and a rapid decrease in the c-axis length with increasing pressure. This anomalous compression reaches a maximum at 8 GPa and the tetragonal lattice behaves normally above 10 GPa, with a nearly constant c/a axial ratio. The rapid rise in the superconducting transition temperature (T(c)) to 41 K with increasing pressure is correlated with this anomalous compression, and a decrease in T(c) is observed above 10 GPa. We present P-V data or the equation of state for EuFe(2)As(2) both in the ambient tetragonal phase and in the high pressure collapsed tetragonal phase up to 70 GPa.
authors.affiliation: Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA.
authors.forename: Walter
authors.initials: W
authors.lastname: Uhoya
authors.forename: Georgiy
authors.initials: G
authors.lastname: Tsoi
authors.forename: Yogesh K
authors.initials: YK
authors.lastname: Vohra
authors.forename: Michael A
authors.initials: MA
authors.lastname: McGuire
authors.forename: Athena S
authors.initials: AS
authors.lastname: Sefat
authors.forename: Brian C
authors.initials: BC
authors.lastname: Sales
authors.forename: David
authors.initials: D
authors.lastname: Mandrus
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Weir