Magnetoresistance: the Hall effect in composite aluminium cryoconductors

• Published in: Cryogenics (Guildford) 1989-07, Vol.29 (7), p.748-752
• Main Authors: Eckels, P.W., Iyer, N.C., Patterson, A., Male, A.T., Parker, J.H., Coltman, J.W.
• Format: Article
• Language: English
• Subjects: aluminium; conductors; Hall effect; magnetoresistance
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/0011-2275(89)90143-4

High purity aluminium has electrical characteristics that are attractive for applications in cryogenic equipment, but the metal has very low intrinsic strength and must be supported in nearly all applications. A composite conductor having an outer sheath of high strength AlFeCe alloy (Alcoa CU-78) and a single inner core of high purity aluminium has been successfully fabricated into lengths suitable for coil winding and testing. Resistivity and magnetoresistivity as a function of temperature have been determined. While residual resistance ratios of the pure material within the composite under zero applied field are in the range of 10 000, the magnetoresistance of the high purity aluminium within the composite appears to be very large when compared to that of pure aluminium wire. The mechanism of magnetoresistivity increase has been related to Hall generation within the composite and the computed apparent magnetoresistivity is in satisfactory agreement with the measured values. The Hall generation model appears to have wider application than just within the composite tested. Further testing of a practical conductor having properties approximating those of pure aluminium is under way.