Laboratory of Resonance Properties of Ordered Magnetic Materials
The Laboratory of Resonance Properties of Ordered Magnetic Materials was organized on December 27, 1971. From the first days it has been headed by Doctor of Phys. and Math. Sciences, Professor, Honored Scientist of the Russian Federation German A. PETRAKOVSKII. Now it has been headed by Doctor of Phys. and Math. Sciences Anatoly Pankraz .
The basic directions of the Laboratory activity are search and synthesis of new magnetic materials, study of magnetic structure, phase transitions, magnetic, resonance and transport properties of different materials, for example, nonmetal magnetics based on transition and rare earth metals, including copper oxide compounds, manganites, ferroborates, chalcogenides of 3d metals, substances in nonequilibrium state (amorphous and optically excited systems).
The following basic methods of synthesis and investigations are being used:
- solution-melt synthesis of single crystals, amorphization from melt, solid-state reaction synthesis;
- study of static magnetic and electric characteristics of magnetics, including SQUID- magnetometry and measurement of electric resistivity;
- study of resonance properties of nonmetal magnetics by methods of ESR, AFMR (in stationary and pulse magnetic fields), double radio-optical resonance;
- analytical calculations and computational modeling of an experiment
The measurements are being undertaken in a wide temperature range (4,2…300 K) and magnetic fields up to 120 kOe.
The synthesis of a series of single crystals of copper oxide compounds and copper and manganese germanates has been performed. Peculiarities of magnetic ordering and properties of magnetics with different magnetic dimensionality and phase transition types have been studied (spin-Peierls magnetic CuGeO3, incommensurate magnetic structure and phase magnetic diagrams in CuB2O4, transition into amorphous state in Bi2Fe4O9, CuGa2O4 spin glass etc.). The effects of negative colossal magnetoresistance in solid solutions FexMn1-xS, CrxMn1-xS, CuVxCr1-xS2 have been found. The state with phase separation and its role in formation of magnetic and transport properties of manganites in the (La1-xEux)0.7Pb0.3Mn3O3 system have been studied. For the first time, photomagnetic effects in different systems have been found and investigated, for example: polarization-dependent change of a magnetic state in hematite single crystals doped with Er and Yb ions; photoinduced transition between states in bistable regime at nonlinear magnetic resonance in (CH3NH3)2CuCl4; change of the interlayer magnetic interaction in trilayer Fe/Si/Fe films induced by optical radiation.
The Laboratory scientists carry out joint research with the Russian scientific centers (P.L. Kapitza Institute for Physical Problems RAS, Moscow, A.V. Nikolaev Institute of Inorganic Chemistry SD RAS, Novosibirsk) and the foreign scientific institutions (Laue-Langevin Institute, Grenoble, France; Paul Scherrer Institute, Zurich, Switzerland; Technical University of Munich, Germany; Fukui Institute, Japan; Institute of Physics of Polish Academy of Science, Warsaw, Poland; Institute of Physics of Solids and Semiconductors, Minsk, Belarus; Donetsk Physicotechnical Institute, Ukraine; Tavrical National University, Simferopol, Ukraine).
The current Laboratory staff includes 5 Doctors and 12 Candidates of Sciences, 5 post-graduate students.
The Laboratory researchers have published over 400 works in Russian and foreign scientific journals and 30 certificate of authorship and patents. The most significant results are reported in the following papers:
- G.À. Petrakovskii. Amorphous magnetics. UFN, 1981, v.134, issue 2, pp.305-391.
- G.À. Petrakovskii, L.S. Emelyanova, I.Ò. Êîkov, G.V. Bondarenko et al. Electronic paramagnetic resonance and spin dynamics of two-dimensional diamagnetically deluted crystals Rb2MnxCd1-xCl4. ZhETF, 1982, v.83, issue 6(12), pp.2176-2184.
- G.À. Petrakovskii, G.S. Patrin. Influence of optical excitation of paramagnetic holmium ions on magnetic resonance in yttrium ferrite -garnet. ZhETF, 1986, 90, v.5, pp.1769-1780.
- B. Roessli, J. Shefer, G.A. Petrakovskii, B. Ouladdiaf, et al. Formation of a Magnetic Soliton Lattice in Copper Metaborate. Phys. Rev. Lett., 2001, v.86, ¹9, p.1885-1888.
- N.V. Volkov, G.A. Petrakovskii, V.N. Vasiliev, K.A. Sablina, åt al. Magnetic resonance probe of the phase separation in Er0.7Pb0.3Mn03 single crystal. JMMM, 2003, v.258-259, p.302-305.
- À.I. Pankrats, G.À. Petrakovskii, Ì.À. Popov, Ê.À. Sablina et al. New magnetic states in CuB2O4 metoborate. Pis’ma v ZhETF, 2003, v.78, issue 9, pp.1058-1062.