Andreenko Alexander Stepanovich

Doctor of Physics and Mathematics(1994),

Reseach interests:
Magnetism, rare earth alloys and compounds, amorphous alloys, phase transitions.

Number of publications: 120.

Main results of science activity:

In 1971-1984 investigations of magnetocaloric effect in rare earth metals, compounds and alloys were taken. The anomalous high magnetocaloric effect in these objects was discovered. It was proved that phase diagrams of heavy rare earth metals and their alloys are complicated - first type phase transition curve transforms into second type transition curve in Lifshits point. It was obtained that when some monocrystals of rare earth alloys are magnetized along difficult axis, a spin-reorientation phase transition happens. Investigations of magnetocaloric effect near compensation temperature made it possible to assume that magnetic field induced non-collinear magnetic structures.

In 1980-1999 researches of magnetic and magnetoelastic properties of rare earth alloys were produced. It was proved that magnetization processes are determined by correlation between exchange interaction energy and random magnetic anisotropy. A model was proposed, describing magnetization and remagnetization in such magnets. It was shown that reorientation of induced magnetic anisotropy axis is anomalous. Examination of magnetic properties under hydrostatic pressure led to determination of how exchange integrals depend on distance between ions. Also it was found that hydroganisation of amorphous alloys acts similar to "negative" hydrostatic pressure. Investigations of magnetoacoustic effects in binary structures magnetostriction amorphous film - piezoelectric were taken.

Several Publications:

1) Andreenko A.S., Zvezdin A.K., Nikitin S.A., Popkov A.F. JETF, 1979,76,6, 2158-2165
2) Andreenko A.S.,Belov K.P., Nikitin S.A.,Tishin A.M. UFN, 1989,158, 4, 27, 553-579/
3) Andreenko A.S., Zvezdin A.K., Nikitin S.A, Utochkin S.N, Saiko G.V., Cheshlya D.Yu. JETF, 1991, 72,2,524-534.
4) Andreenko A.S., Nikitin S.A., Spichkin Yu.I. JMMM, 1993, 118,142-146.
5) Andreenko A.S., Nikitin S.A., UFN ,1997,167, 6, 605-622

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