Observation of quantum Griffiths singularity and ferromagnetism at the superconducting LaAlO3/SrTiO3(110) interface

摘要

Diverse phenomena emerge at the interface between band insulators LaAlO3 and SrTiO3, 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 LaAlO3/SrTiO3(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 LaAlO3/SrTiO3(110) interface, which suggests the potential coexistence of superconductivity and ferromagnetism.