Hidden non-Fermi liquid behavior caused by magnetic phase transition in Ni-doped Ba-122 pnictides

TL;DR

This study reveals hidden non-Fermi liquid behavior linked to magnetic phase transitions in Ni-doped Ba-122 pnictides, observed through optical spectroscopy and Drude-Lorentz modeling, highlighting doping-dependent electronic scattering properties.

Contribution

It uncovers the temperature-dependent scattering rate behavior in Ni-doped Ba-122, demonstrating a hidden non-Fermi liquid state associated with magnetic transitions.

Findings

Hidden quasi-linear scattering rate in underdoped samples

Quadratic scattering rate in optimally doped samples

Magnetic phase transition correlates with non-Fermi liquid behavior

Abstract

We studied two BaFe2-xNixAs2 (Ni-doped Ba-122) single crystals at two dfferent 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.