  Pd is one of the metals suitable for inducing low-temperature crystallization
in Ge. However, it is not clear how residual Pd atoms are integrated into the
Ge lattice. Therefore, time-differential perturbed angular correlations (TDPAC)
technique using the 100Pd(100Rh) nuclear probe produced by recoil implantation
has been applied to study the hyperfine interactions of this probe in
single-crystalline undoped Ge. A Pd-vacancy complex aligned along the <111>
crystallographic direction with a unique interaction frequency of 8.4(5) Mrad/s
has been identified. This complex was measured to have a maximum relative
fraction of about 76(4)% following annealing at 350 oC. Further annealing at
higher temperatures reduced this fraction, possibly via dissociation of the
complex. Calculations suggest dissociation energy of 1.94(5) eV for the
complex. DFT calculations performed in this work are in reasonable good
agreement with the experimental values for the electric-field gradient of the
defect complex in Ge. The calculations predict a split-vacancy configuration
with the Pd on a bond-centred interstitial site having a nearest-neighbour
semi-vacancy on both sides (V-PdBI-V).
