Magnetism and absolute zero

The very cold temperature of 0.5°K was reached, advancing the study of low-temperature physics and magnetism. Additionally, it was theorized that by placing a paramagnetic substance in contact with this liquid helium into a magnetic field, the temperature should consistently drop even lower. This remained untested for another decade.
 Willem Hendrik Keesom Netherlands 1925 Magnetism and absolute zero

The very cold temperature of 0.5°K was reached, advancing the study of low-temperature physics and magnetism. Additionally, it was theorized that by placing a paramagnetic substance in contact with this liquid helium into a magnetic field, the temperature should consistently drop even lower. This remained untested for another decade.