which have ferromagnetic properties at these temperatures....http://www.google.es/patents/US6798095?utm_source=gb-gplus-sharePatente US6798095 - Device including component, which is ferromagnetic in cryogenic temperature range and can be subjected to mechanical loads B???squeda avanzada de patentes N???mero de publicaci???nUS6798095 B2Tipo de publicaci???nConcesi???n N???mero de solicitudUS 10/398