A superconductor crystal is squeezed in a small cell, like clamping it in a vise, but with water to distribute the pressure evenly. Pressure up to 1.08 GPa (about a hundred times greater than in a car tire) barely changes the temperature at which the material loses resistance. But it noticeably enhances its ability to carry current without loss in a magnetic field — the so-called critical current.
Inside the superconductor, the magnetic field twists into vortices, like tiny tornadoes. These vortices can move and interfere with the current. After compression, the vortices slowed down — by 40% at 8 K (−265 °C) and a field of 0.5 T. And the critical current tripled. The reason lies in microcracks that remain in the crystal after pressure is released: they act as pinning points, holding the vortices in place.
Surprisingly, the improvements do not vanish after the pressure is released. The crystal seems to remember being compressed. This opens a simple path to improving superconductors: no need to add impurities or create artificial defects with complex methods, just squeeze and release the material a few times. Such a "workout" is enough to make the current flow noticeably better.
A pressure of 1 GPa is roughly the weight of a hundred cars stacked on an area the size of a fingernail.