GALVANOMAGNETIC PROPERTIES OF METALS ATBOILING OF LIQUID HELIUM

Galvanomagnetic properties of metals at boiling point of liquid helium and some prob-lems relating to Joule heating in cylinder conductors are investigated by the method of voltage current characteristics. Radial current under an external coaxial magnetic field is used to get high magnetoresistance of conductor. High level of magnetore-sistance in this geometry offers the possibility to investigate a wide range of heat generation. The stabilization of voltage observed in definite current range is discussed in terms of analysis of heat aspects of problem when a heat genemtion function and heat elimination they are regarded at helium temperuture. An electric temperature ordering of system is proposed as a factor responsible for voltage stabilization when the presence of more heated and less heated sections along conductor radius is connected with negativity of derivative of heat elimination function with respect to temperature between first and second boiling crisis.

Electronic Structures and Magneto-Transport Properties of Co-Based Heusler Alloy Based Magneto-Resistance Junctions

A direct link between band structure and the ballistic transport property of full-Heusler alloys based Co2YZ/Al/Co2YZ trilayers (Y = Sc, Ti, V, Cr, Mn and Fe; Z = Al, Si and Ge) has been studied by firstprinciples calculations. It is found that the transport efficiency is determined primarily by three factors related to band structure: the shape of the band crossing Fermi energy EF, the distance d of the two intersection points of Co2YZ and Al at EF, and the absolute maximum of the energy lying in the EF-crossing band, |Emax|. The transmission coefficient distribution patterns imply that the affected factor of magneto-resistance (MR) ratio is attributed to the band features around EF. In general, an intuitively illustrated diagram is proposed to clarify the relationship between the probability of electron transition and the current magnitude. © 2017, Shanghai Jiaotong University and Springer-Verlag GmbH Germany.