  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.
