  The main driven force of the electronic nematic phase in iron-based
superconductors is still under debate. Here, we report a comprehensive study on
the nematic fluctuations in a non-superconducting iron pnictide system
BaFe$_{1.9-x}$Ni$_{0.1}$Cr$_{x}$As$_{2}$ by electronic transport,
angle-resolved photoemission spectroscopy (ARPES) and inelastic neutron
scattering (INS) measurements. Previous neutron diffraction and transport
measurements suggested that the collinear antiferromagnetism persists to
$x=0.8$, with similar N\'{e}el temperature $T_N$ and structural transition
temperature $T_s$ around 32 K, but the charge carriers change from electron
type to hole type around $x=$ 0.5. In this study, we have found that the
in-plane resistivity anisotropy also highly depends on the Cr dopings and the
type of charge carriers. While ARPES measurements suggest possibly weak orbital
anisotropy onset near $T_s$ for both $x=0.05$ and $x=0.5$ compounds, INS
experiments reveal clearly different onset temperatures of low-energy spin
excitation anisotropy, which is likely related to the energy scale of spin
nematicity. These results suggest that the interplay between the local spins on
Fe atoms and the itinerant electrons on Fermi surfaces is crucial to the
nematic fluctuations of iron pnictides, where the orbital degree of freedom may
behave differently from the spin degree of freedom, and the transport
properties are intimately related to the spin dynamics.
