Abstract
We perform a simple model calculation of the effects of electron focusing on the transport properties of a semiinfinite metallic slab in the presence of a magnetic field. We consider, in particular, the case in which current is fed into the slab through two superconducting strips, with the field applied parallel to the strips. A thin resistive layer is assumed to exist on the surface of the metal. We treat the cases of short and long mean free paths compared with the separation of the leads. For the latter case we derive an integral equation relating the normally flowing current to the potential at the surface. This equation is used to study the magnetoresistance for three models of the Fermi surface: a free-electron-like surface, a compensated free-electron, free-hole-like surface, and a compensated surface composed of three free-electron-like sheets and one free-hole-like sheet. This latter model is topologically equivalent to the Bi case. The results of the calculation agree qualitatively with the experimental results for fields of the order of and larger than the focusing field.
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Work supported in part by the National Science Foundation through Grant GH 34438.
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Gonçalves da Silva, C.E.T. Electron focusing and Fermi surface diameter. J Low Temp Phys 16, 337–348 (1974). https://doi.org/10.1007/BF00655323
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DOI: https://doi.org/10.1007/BF00655323