Vortex confinement by columnar defects in ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ crystals: Enhanced pinning at high fields and temperatures

We report the realization of a microstructure which leads to very strong high-temperature flux pinning in ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ crystals. Aligned discontinuous columns of damaged material, about 50 Å in diameter and more than 15 μm long, are produced by 580-MeV Sn-ion irradiation. The enhancement of flux pinning is largest when the applied magnetic field is aligned with these tracks. At high temperatures and fields the pinning is much greater than that produced by random point defects, and causes a considerable enlargement of the irreversibility region in the H-T plane.