The Tripe Marketing Board presents A Brief History of Fridge Magnets:
BONUS: The history continues past that point, of course. Part of it is documented in this study:
“Design, manufacture, and test of an adiabatic demagnetization Refrigerator Magnet for use in space,” Steve Milward, Stephen Harrison, Robin Stafford Allen, Ian D. Hepburn, Christine Brockley-Blatt [pictured here], IEEE Transactions on Applied Superconductivity, vol. 15, no. 2, pp. 1477-1479, 2005. The authors explain:
“The proposed European Space Agency (ESA) XEUS mission will use an adiabatic demagnetization refrigeration (ADR) system to cool X-ray detectors to a temperature of less than 0.1 K. The superconducting magnet for the flight standard prototype is currently under construction by Space Cryomagnetics Ltd of Culham, England. The magnet is subject to tight constraints on its mass, stray field, and power consumption. This paper describes the design, manufacture and test of the magnet.”