  The Anomalous Hall Effect (AHE) is an important quantity in determining the
properties and understanding the behavior of the two-dimensional electron
system forming at the interface of SrTiO3-based oxide heterostructures. The
occurrence of AHE is often interpreted as a signature of ferromagnetism, but it
is becoming more and more clear that also paramagnets may contribute to AHE. We
studied the influence of magnetic ions by measuring intermixed
LaAlO3/GdTiO3/SrTiO3 at temperatures below 10 K. We find that, as function of
gate voltage, the system undergoes a Lifshitz transition, while at the same
time an onset of AHE is observed. However, we do not observe clear signs of
ferromagnetism. We argue the AHE to be due to the change in Rashba spin-orbit
coupling at the Lifshitz transition and conclude that also paramagnetic moments
which are easily polarizable at low temperatures and high magnetic filds lead
to the presence of AHE, which needs to be taken into account when extracting
carrier densities and mobilities.
