Heterostructures made of a layer of a cuprate insulator $\mathrm{L}{\mathrm{a}}_2\mathrm{Cu}{\mathrm{O}}_4$ on the top of a layer of a nonsuperconducting cuprate metal $\mathrm{L}{\mathrm{a}}_{1.55}\mathrm{S}{\mathrm{r}}_{0.45}\mathrm{Cu}{\mathrm{O}}_4$ show high-$T_c$ interface superconductivity confined within a single $\mathrm{Cu}{\mathrm{O}}_2$ plane. Given this extreme quasi-two-dimensional quantum confinement, it is of interest to find out how interface superconductivity behaves when exposed to an external magnetic field. With this motivation, we have performed contactless tunnel-diode-oscillator-based measurements in pulsed magnetic fields up to 56 T as well as measurements of the complex mutual inductance between a spiral coil and the film in static fields up to 3 T. Remarkably, we observe that interface superconductivity survives up to very high perpendicular fields, in excess of 40 T. In addition, the critical magnetic field $H_m\left(T\right)$ reveals an upward divergence with decreasing temperature, in line with vortex melting as in bulk superconducting cuprates.

• Received 11 March 2016
• Revised 3 June 2016

DOI:https://doi.org/10.1103/PhysRevB.94.014507