Observation of Hexagonally Ordered Flux Quanta in YBa sub 2 Cu sub 3 0 sub 7
30 November 1987
The high resolution Bitter Pattern Technique has been used to reveal the magnetic structure of single crystal samples of the high T sub c superconductor YBa sub 2 Cu sub 3 0 sub 7 at 4.2K. The patterns are strongly reminiscent of the analogous structures in low T sub c, type II superconductors. The implications are that the crystals are uniform superconductors with a magnetic structure consisting of singly quantized vortices of quantum hc/2e and with a tendency to form hexagonally ordered arrays.: