Grigorii Mikitik, Leading Researcher.
(Г.П. Микитик)
E-mail: mikitik@ilt.kharkov.ua
Graduated from Novosibirsk State University (Russia) in 1973.
PhD Phys & Math, ILTPE ,1982.
DSc Phys & Math, ILTPE, 2008
Academic Positions: 1973–1978, junior researcher, Institute of Automation and Electrometry, Siberian Branch of the USSR Academy of Sciences, Novosibirsk, Russia. Since 1978 has been working at Institute for Low Temperature Physics and Engineering (ILTPE), Kharkov, Ukraine. During 1998 - 2010 invited scientist at Max Planck Institute (Stuttgart, Germany).
Fields of scientific interest:
1. H-T Phase Diagrams, Vortex Pinning, Critical States, and Flux Creep in Type-II Superconductors.
In particular, the H-T phase diagrams of type-II superconductors were analyzed, taking into account thermal fluctuations of the order parameter and flux-line pinning [13,17,36,38,46,53,97]. The complete set of the critical state equations for thin flat anisotropic superconductors was derived [31,59,71], and a number of critical state problems were solved (see Reviews [88,94]), including the problem of the vortex-shaking effect [37,41,49,72]. Effects of a sample shape and of anisotropy of the flux-line pinning on magnetic relaxation in type-II superconductors were studied [20,24,30,39,47,56]. Vortex penetration into thin superconducting samples was analyzed, taking into account an interplay between the Bean-Livingston and the geometrical barriers for vortices in the superconductors [95].
2. Electron Properties of Crystals with Degenerate Electron Energy Bands.
The main problems that have been studied: the semiclassical quantization rule for an electron in a magnetic field in crystals with degenerate electron energy bands [23,26]; the g factors of electron orbits [40,45,57]; the magnetization of electrons in crystals with degenerate or nearly degenerate bands [11,18,28,48,58,75], including topological semimetals [102,105,106]; the Berry phase in metals [26,58,74], in graphene [65,76,78], and in topological insulators [93]; electron topological transitions of 3.5 kind in crystals [98,100,101,103]; spontaneous symmetry breaking of magnetostriction in metals [99] (i.e., a counterpart of the Jahn-Teller effect for crystalline solids with unlocalized electrons).
Brief description of the research area and the obtained results: Degeneracy of the electron energy bands frequently occurs in crystals (and the topological semimetals are among them). In the crystals with inversion symmetry and weak spin-orbit interaction such degeneracy mainly takes place along the band-contact lines in the Brillouin zone. It was shown that if the electron orbit links with a band-contact line, an additional term appears in the well-known Onzager-Lifshits-Kosevich quantization rule. This term is a manifestation of the Berry phase. The modification of the quantization rule can be experimentally discovered as a change in the phase of the de Haas - van Alphen and Shubnikov - de Haas oscillations. This change enables one to detect the band-contact lines in crystals. If the spin-orbit interaction is taken into account, the Berry phase manifests itself as a large g factor of electron orbits even for a weak spin-orbit coupling. The band-contact lines cause the emergence of the electron topological transitions of 3.5 kind in metals. The types of the electron-energy-band degeneracy in crystals were found which lead to the so-called giant anomalies of the magnetic susceptibility in weak magnetic fields. These types cover the degeneracies occuring in the topological semimetals. For all these types, the electron magnetization was calculated both at weak and strong magnetic fields.