demagnetization

Demagnetization is the process of removing magnetic properties from a material. A specific method, known as adiabatic demagnetization, is used to cool materials to extremely low temperatures, often a fraction of 1 Kelvin. This technique was proposed by chemists Peter Debye and William Francis Giauque.123

The process involves using a paramagnetic salt at very low temperatures. When a magnetic field is applied, the magnetic dipoles within the material align. If the material is then insulated from its surroundings (an adiabatic process) and the magnetic field is removed, the dipoles become randomly oriented again, causing the material to cool significantly. This method can achieve temperatures as low as 0.0015 K. Even lower temperatures can be reached through adiabatic nuclear demagnetization, which aligns nuclear dipoles.3