Scanning SQUID Imaging of Noncollinear Antiferromagnetic Domains in EuTiO₃ film

Magnetic and ferroelectric instabilities in antiferromagnet EuTiO₃ provide a rare platform to study multiferroic quantum critical phenomena and strong magnetoelectric couplings. Despite extensive experimental efforts, the magnetic structure remains without consensus. Neutron diffraction analysis is inconclusive due to large neutron absorption. Uncertainty arises in X-ray magnetic scattering due to the presence of magnetic domains. Here, we report temperature dependent local magnetic measurements of a thin film of EuTiO₃ deposited on SrTiO₃ using a scanning superconducting quantum interference device (SQUID) microscope. Magnetic flux and susceptibility images reveal the formation of weakly ferromagnetic domains below the film’s Néel temperature, indicative of a noncollinear or canted antiferromagnetic state. Noncollinear magnetic ordering lowers the magnetic symmetry of EuTiO₃, which may influence current interpretations of magnetoelectric and magnetoelastic effects and predictions of quantum critical behavior.