Modulated Susceptibility in Thin Film LBCO

In addition to being the first instance of high temperature superconductivity in the cuprate perovskite superconductors, lanthanum barium copper oxide (La_2-xBa_xCuO₄) has garnered recent interest for nematicity and interesting behavior at 1/8^th doping. In this experiment, we used Scanning Superconducting Quantum Interference Device (SQUID) Microscopy to spatially resolve the magnetic fields and susceptibility in a number of thin film LBCO samples with doping in the vicinity of the 1/8^th anomaly. We measured the critical temperatures and superfluid densities of the samples at various positions. We observed strong stripe-like modulations in the susceptibility (“striae”) of multiple samples with the surprisingly long periods of 2-4um. The periods of these striae are 1000 times longer than the periods of stripes observed in similar samples using such techniques as neutron diffraction. We speculate on the sources of these effects.