Abstract

The high-resolution Bitter pattern technique has been used to reveal the magnetic structure of single-crystal samples of high-${T}_{c}$ superconductor Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ at 4.2 K. Typical patterns consist of hexagonally correlated, singly quantized vortices of flux $\frac{\mathrm{hc}}{2e}$. That is, the structures are comparable to those that would be observed in conventional type-II superconductors under similar conditions.