Observation of quantum Griffiths singularity and ferromagnetism at the superconducting LaAl O 3 / SrTi O 3 ( 110 ) interface

Diverse phenomena emerge at the interface between band insulators $\mathrm{LaAl}{\mathrm{O}}_{3}$ and $\mathrm{SrTi}{\mathrm{O}}_{3}$, such as superconductivity and ferromagnetism, showing an opportunity for potential applications as well as contributing to fundamental research interests. Here, we report the superconductor-metal transition driven by a perpendicular magnetic field in superconducting two-dimensional electron gas formed at the $\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}(110)$ interface, which offers an appealing platform for quantum phase transition from a superconductor to a weakly localized metal. Interestingly, when approaching the quantum critical point, the dynamic critical exponent is not a constant but a diverging value, which is direct evidence of a quantum Griffiths singularity arising from quenched disorder at ultralow temperatures. Furthermore, the hysteretic property of magnetoresistance is observed at the $\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}(110)$ interface, which suggests the potential coexistence of superconductivity and ferromagnetism.