  Hysteretic magnetoresistance (MR) is often used as a signature of
ferromagnetism in conducting oxide thin films and heterostructures. Here,
magnetotransport is investigated in a non-magnetic uniformly La-doped SrSnO3
film grown using hybrid molecular beam epitaxy. A 12 nm La:SrSnO3/2 nm
SrSnO3/GdScO3 (110) film with insulating behavior exhibited a robust hysteresis
loop in the MR at T < 5 K accompanied by an anomaly at ~ +/- 3 T at T < 2.5 K.
Furthermore, MR with the field in-plane yielded a value exceeded 100% at 1.8 K.
Using detailed temperature-, angle- and magnetic field-dependent resistance
measurements, we illustrate the origin of hysteresis is not due to magnetism in
the film but rather is associated with the magnetocaloric effect of the GdScO3
substrate. Given GdScO3 and similar substrates are commonly used in complex
oxide research, this work highlights the importance of thermal coupling to
processes in the substrates which must be carefully accounted for in the data
interpretation for thin films and heterostructures utilizing these substrates.
