The late 50`s of the last century were marked by obtaining many impressive results in physics. Particularly, the phenomenon of superconductivity remained uncertain nearly five decades after its discovery. It was only in 1957 when the American physicists J. Bardeen, L. N. Cooper and J. R. Schrieffer discovered a mechanism which explained the phenomenon by the formation of electron pairs bound by means of their interaction with crystal lattice phonons. The electron pairs can participate in the phenomenon of the Bose-Einstein condensation (BEC) and contribute to the formation of a coherent macroscopic state called "Bose-Einstein condensate" with properties of superfluid liquid.

In 1958 the young researcher Vsevolod Moskalenko from the State University in Chisinau came to the M.V.Lomonosov Moscow State University, and he got into the enormous agitation and boiling reigning at scientific seminars, especially at well-known scientific schools of N.N. Bogoliubov, L.D. Landau and V.L. Ghinzburg, where various aspects of the superconductivity theory proposed by Bardeen, Cooper and Schrieffer were being discussed. The scientists realized the need to generalize the existing theory based on an ideal model of the metal with a single electronic energy band, which did not correspond to real superconductors. This problem was solved in the same 1958 year by the young researcher Vsevolod Moskalenko, who proposed for the first time a model of superconductor with two electronic bands superimposed in the region of the Fermi energy. According to the generalized theory of superconductivity, the Cooper pairs can be integrally transferred from one energy band to another one, which gives rise to the electronic inter-band interaction concomitantly with the intra-band interaction. The presence of the additional interactions contribute to the increasing of the binding energy of the Cooper pair, and to the increasing of the critical temperature of the phase transition from the normal metal state to the superconducting state.

The new theory paved the way to the explanation of the existence of high critical temperature superconductors, known in the literature as HTSC (high temperature superconductivity). The theory explained not only qualitatively, but also quantitatively the thermodynamic and magnetic properties of tow-band superconductors as compared to the one-band model. The work elaborated and sent to publication in 1958 was published in Physics of Metals and Metallography “Физика металлов и металловедение”, in 1959. One year later, the american physicists H. Suhl, B.T. Matthias, and L. R. Wallker developed independently the theory of two-band superconductivity, the respective paper being submitted and published at the end of 1959.

Academician Vsevolod Moscalenco founded a new scientific direction - investigation of superconductors with anisotropic and multi-band energy spectra. The discovery in 1986 of high-temperature superconductivity (100 K) in ceramic oxides essentially influenced the further development of the HTSC theory of multi-energy-band superconductors, while the theory based on the V. A. Moskalenko model has become a classic one. 20 PhD theses and 5 doctor habilitat theses were defended during the years in the framework of the scientific school founded by the academician Vsevolod Moskalenko at the Academy of Sciences of Moldova, which were based on many hundreds of scientific works, including 6 monographs.

Academician Ion Tighineanu,
First Vice-President of the Academy of Sciences of Moldova