  Amorphous thin films of Tb$_{17}$Co$_{83}$ (a-Tb-Co) grown by magnetron
co-sputtering exhibit changes in magnetic anisotropy with varying growth and
annealing temperatures. The magnetic anisotropy constant increases with
increasing growth temperature, which is reduced or vanishes upon annealing at
temperatures above the growth temperature. The proposed explanation for this
growth-induced anisotropy in high orbital moment Tb-based transition metal
alloys such as a-Tb-Co is an amorphous phase texturing with preferential
in-plane and out-of-plane local bonding configurations for the rare-earth and
transition metal atoms. Scanning nanodiffraction performed in a transmission
electron microscope (TEM) is applied to a-Tb$_{17}$Co$_{83}$ films deposited
over a range of temperatures to measure relative changes in medium-range
ordering (MRO). These measurements reveal an increase in MRO with higher growth
temperatures and a decrease in MRO with higher annealing temperatures. The
trend in MRO indicates a relationship between the magnetic anisotropy and local
atomic ordering. Tilting select films between 0$^{\circ}$ and 40$^{\circ}$ in
the TEM measures variations in the local atomic structure a function of
orientation within the films. The findings support claims that preferential
ordering along the growth direction results from temperature-mediated adatom
configurations during deposition, and that oriented MRO correlates with the
larger anisotropy constants.
