Electronic devices, which exploit the spin as well as charge of the electron, have attracted much interest over the last several years. This interest in ‗‗spintronics‘‘ is stimulated by expected industrial applications, such as magnetic tunnel junctions based sensors, magnetic random access memory, as well as basic physics, offering new ways to manipulate quantum states using these two fundamental properties of the electron. In nanoscale magnetic devices, such as single-electron transistors [1], the presence of a Coulomb blockade makes the charge transport sensitive to a very few electron states, which results in a number of pronounced effects in magnetoconductance. Glass-coated single-crystal microwires of Bi and Bi-Sb were prepared by the Ulitovsky method [2], when using technique of local laser heating the nanoconstrictions were fabricated. We investigated the tunnel junctions obtained in Bi and Bi0.97Sb0.03 nanoconstrictions at various temperatures and different potentials on the gate electrode. Current–voltage characteristics of tunnel junctions are shown in Fig. 1. We observed a change in the tunneling current depending on the potential on the gate electrode. This difference ΔI/I=0.26 is a manifestation of the electrical field effect. The dependences of the tunneling current on the longitudinal and transverse magnetic fields up to 14 T were also investigated. Various approaches to explain the obtained results are discussed.