Grigorii Mikitik, Senior Researcher.

E-mail: mikitik@ilt.kharkov.ua

Graduated from Novosibirsk State University (Russia) in 1973.

PhD Phys & Math, ILTPE ,1982.

Academic Positions: 1973–1979, junior researcher, Institute of Automation and Electrometry, Siberian Branch of the USSR Academy of Sciences, Novosibirsk, Russia. Since 1979 has been working at ILTPE. During 1998 - 2003 invited scientist at Max Planck Institute (Stuttgart, Germany). Publications: 59.

Fields of scientific interest:

 H-T Phase Diagrams of Type-II Superconductors. Critical State and Flux Creep

The H-T phase diagrams of type-II superconductors were analyzed, taking into account thermal fluctuations of the order parameter and flux-line pinning. In particular, the effect of pinning on the vortex-lattice-melting line and on its upper critical point was considered. The complete set of the critical state equations for thin flat anisotropic superconductors was derived and analyzed. On the basis of this analysis the vortex-shaking effect was explained. Effects of a sample shape and of anisotropy of the flux-line pinning on magnetic relaxation in type-II superconductors were studied (G.P. Mikitik and I.M. Babich).

Electron Properties of Crystals with Degenerate Electron Energy Bands

The following problems have been studied in the framework of the issue: the semiclassical quantization rule for the crystals with degenerate electron energy bands, g factors of the electron orbits, the magnetization of electrons in crystals with degenerate or nearly degenerate bands.

Degeneracy of the electron energy bands frequently occurs in crystals. In the crystals with inversion symmetry and weak spin-orbit interaction such a 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 of the phase in the de Haas–van Alphen effect 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 even for a weak spin-orbit coupling.

The types of the band degeneracy were found which lead to the so-called giant anomalies of the magnetic susceptibility in weak magnetic fields. For all these types, the smooth (nonoscillating) part of the electron magnetization was calculated both at weak and strong magnetic fields (G.P. Mikitik and Yu.V. Sharlai).

Selected publications:

1. G.P. Mikitik, Zh. Exsp. Teor. Fiz 101, 1042 (1992) [Sov. Phys. JETP 74, 558 (1992)]

2. G.P. Mikitik, E.H. Brandt, PRB 64, 184514 (2001).

3. G.P. Mikitik, E.H. Brandt, Phys. Rev. Lett. 89, 259701 (2002).

4. G.P. Mikitik, E.H. Brandt, PRB 68, 054509 (2003).

5. G.P. Mikitik, E.H. Brandt, PRB 62, 6800 (2000).

6. E.H. Brandt, G.P. Mikitik, Phys. Rev. Lett. 89, 027002 (2002).

7. G.P. Mikitik, E.H. Brandt, PRB 67, 104511 (2003).