Study of high-Tc interface superconductivity in La1.55Sr0.45CuO4/La2CuO4 heterostructures at high magnetic fields and frequencies

We have synthesized heterostructures that consist of a layer of a cuprate insulator, La2CuO4, and a layer of a nonsuperconducting cuprate metal, La1.55Sr0.45CuO4. Such bilayers show high-Tc interface superconductivity confined within a single CuO2 plane. Here, we explore the behavior of interface superconductivity at high frequencies (up to 50 MHz) under high magnetic fields (up to 56 T). We find that interface superconductivity persists up to very high perpendicular fields (exceeding 40 T). The critical magnetic field Hm(T) shows an upward divergence with decreasing temperature suggestive of vortex-lattice melting, similar to what is observed in bulk superconducting cuprates.