Angular dependence of pinning potential, upper critical field, and irreversibility field in underdoped BaFe1.9Co0.1As2 single crystal

Abstract

Underdoped BaFe1.9Co0.1As2 single crystal was studied by angular dependence of magneto-transport at fields up to 13 T over a wide range of temperature. Our results show that pinning potential, Uo, decreases slightly for θ ≤ 45° and remains constant for θ ≥ 45°, while the upper critical field, Hc2, and the irreversibility field, Hirr, increase with θ. According to anisotropic Ginzburg-Landau theory, the anisotropy was determined by scaling the resistivity under different magnetic fields below the superconducting critical temperature, Tc. Anisotropy, Γ, in the underdoped crystal is found to be temperature dependent and decreases from 2.1 to 1.8 for as T is reduced from 17 to 12.5 K.