  SrIrO3, the three-dimensional member of the Ruddlesden-Popper iridates, is a
paramagnetic semimetal characterised by a the delicate interplay between
spin-orbit coupling and Coulomb repulsion. In this work, we study the
anisotropic magnetoresistance (AMR) of SrIrO3 thin films, which is closely
linked to spin-orbit coupling and probes correlations between electronic
transport, magnetic order and orbital states. We show that the low-temperature
negative magnetoresistance is anisotropic with respect to the magnetic field
orientation, and its angular dependence reveals the appearance of a fourfold
symmetric component above a critical magnetic field. We show that this AMR
component is of magnetocrystalline origin, and attribute the observed
transition to a field-induced magnetic state in SrIrO3.
