title: Hidden non-Fermi liquid behavior caused by magnetic phase transition in Ni-doped Ba-122 pnictides.
abstract: We studied two BaFe(2-x)N(I)xAs2 (Ni-doped Ba-122) single crystals at two different doping levels (underdoped and optimally doped) using an optical spectroscopic technique. The underdoped sample shows a magnetic phase transition around 80 K. We analyze the data with a Drude-Lorentz model with two Drude components (D1 and D2). It is known that the narrow D1 component originates from electron carriers in the electron-pockets and the broad D2 mode is from hole carriers in the hole-pockets. While the plasma frequencies of both Drude components and the static scattering rate of the broad D2 component show negligible temperature dependencies, the static scattering rate of the D1 mode shows strong temperature dependence for the both samples. We observed a hidden quasi-linear temperature dependence in the scattering rate of the D1 mode above and below the magnetic transition temperature while in the optimally doped sample the scattering rate shows a more quadratic temperature dependence. The hidden non-Fermi liquid behavior in the underdoped sample seems to be related to the magnetic phase of the material.
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Seokbae
authors.initials: S
authors.lastname: Lee
authors.affiliation: Center for Novel States of Complex Materials Research, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Republic of Korea.
authors.forename: Ki-Young
authors.initials: KY
authors.lastname: Choi
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Eilho
authors.initials: E
authors.lastname: Jung
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Seulki
authors.initials: S
authors.lastname: Rho
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Soohyeon
authors.initials: S
authors.lastname: Shin
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Tuson
authors.initials: T
authors.lastname: Park
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Republic of Korea.
authors.forename: Jungseek
authors.initials: J
authors.lastname: Hwang