A two stage Gifford-McMahon cryocooler having a low temperature stage for reaching approximately 10K, wherein the low temperature stage includes a passive magnetic heat regenerator selected from the group consisting of Er.sub.6 Ni.sub.2 Sn, Er.sub.6 Ni.sub.2 Pb, Er.sub.6 Ni.sub.2 (Sn.sub.0.75 Ga.sub.0.25), and Er.sub.9 Ni.sub.3 Sn comprising a mixture of Er.sub.3 Ni and Er.sub.6 Ni.sub.2 Sn in the microstructure.
ISURF Reference Number
Iowa State University Research Foundation, Inc.,
Gschneidner, Karl A. Jr. and Pecharsky, Vitalij K., "Erbium-based magnetic refrigerant (regenerator) for passive cryocooler" (1996). Iowa State University Patents. 137.