Thermal expansion and anisotropic pressure derivatives of T_c in Ba(Fe_1-xCo_x)₂As₂ single crystals

2009/01/13 by Bud'ko, S. L., Ni, N., Nandi, S. +2
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)

paper · doi:10.48550/arxiv.0901.1800

Abstract

Heat capacity and anisotropic thermal expansion was measured for Ba(Fe_1-xCo_x)₂As₂ (x = 0, 0.038, 0.074) single crystals. Thermal expansion is anisotropic and, in tetragonal phase, is significantly higher along the c-axis. Previously reported phase transitions, including possibly split structural and magnetic for x = 0.038 are clearly seen in both measurements. Uniaxial pressure derivatives of the superconducting transition temperature inferred from the Ehrenfest relation have opposite signs for in-plane and c-axis pressures for both Ba(Fe_0.962Co_0.038)₂As₂ and Ba(Fe_0.926Co_0.074)₂As₂, with the opposite sign of this anisotropy.

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