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Ashot S. Markosyan

 

 

Professor (2001)

 

Doctor of physical and mathematical science

(habilitation degree) (1989)

 

Leading Researcher (1996)

Senior Researcher (1991)

 

 

Postal address

Laboratory of Problems for Magnetism,
Faculty of Physics, M.V. Lomonosov Moscow State University, Vorobjovy gory, 119992 Moscow, Russia

Telephone

+7 (095) 939 1145

FAX

+7 (095) 939 5907

E-mail

marko@plms.phys.msu.ru

 

Research interests

ћ        Magnetism in condensed matter, magnetoelastic phenomena, magnetic and structural phase transitions, low-dimensional magnetism.

ћ        Materials technology.

Main directions of the research activity

ћ        Study of the magnetic and transport properties of R-3d intermetallic compounds with a magnetic instability of the itinerant-electron subsystem.

ћ        Study of the magnetic properties of molecule-based compounds showing a magnetic low-dimensionality.

Main accomplishments

-        Finding and investigation of first-order magnetic phase transitions in RMn2 intermetallic compounds.

-        Finding and experimental investigation of the phenomenon of itinerant-electron metamagnetism in RCo2 intermetallic compounds.

-        Finding and experimental investigation of the phenomenon of temperature-induced itinerant-electron metamagnetism in intermetallic compounds of the RCo3 series.

-        Investigation of the anisotropic magnetostriction of the RCo2 compounds.

-        Theoretical modelling of the paramagnetic properties of molecule-based complexes containing bivalent manganese (Fig. 4).

 

 

Fig. 4. Temperature dependence of the product cT of the molecular complex {Mn(hfac)2}3(3RD)2?n-C7H16 with a rhombohedral crystal structure. TC = 3.4 K. In this complex, the molecules of Mn(hfac)2 (hexafluoroacetylacetonato manganese) with 5/2 spins and the triradical molecules RD containing NO- groups with 1/2 spins form plain layers exchange coupled by a weak interlayer interaction. The dashed line in figure is the computed theoretical temperature variation of cT for the value of the Mn2+-NO- exchange integral equal to -175 K. The increase of cT above 140 K is related to the thermal excitations of the linear spin trimers NO--Mn2+-NO-. Without a molecular structure when magnetism is caused by the ground multiplet only, cT ? const at high temperatures (Curie-Weiss law) [A.S. Markosyan, Y. Hosokoshi, K. Inoue, Phys. Lett. A 261 (1999) 212-216].

 

Educational and teaching work

Supervisor of Ph.D. theses: 6

Supervisor of Diploma works:љ 10

Lecture course for majors, 4th year students of the Faculty of Physics of the Moscow State University, "Introduction to Solid State Physics and Magnetism" (1984-2001)

 

Total number of publications in refereed journals: 170

 

Some recent publications


1.      I.S. Dubenko, I.Yu. Gaidukova, E. Gratz, K. Inoue, A.S. Markosyan, V.E. Rodimin, Magnetic instability of the Co sublattice in the Ho1‑xYxCo3 system, Physica B 319 (2002) 21-27.

2.      E. Gratz, A.S. Markosyan, Physical properties of RCo2 Laves phases, J. Phys.: Condens. Matter 13 (2001) R385-R413.

3.      M. Tanaka, Y. Hosokoshi, A.S. Markosyan, H. Iwamura, K. Inoue, Magnetic properties of layered complexes [M(hfac)2]3(R)2, M=Mn(II) and Cu(II), with trisnitroxide radicals having various metal-radical exchange interactions, J. Phys.: Condens. Matter 13 (2001) 7429-7442.

4.      R. Hauser, E. Bauer, E. Gratz, H. Mueller, M. Rotter, H. Michor, G. Hilsher, A.S. Markosyan, G. Kamishima, T. Goto, Decoupling of the magnetic ordering of the rare earth and the Co sublattices Er1-xYxCo2 compounds driven by substitution or pressure, Phys. Rev. B 61 (2000) 1198-1210.

5.      H. Kumagai, A.S. Markosyan, K. Inoue, Synthesis, structure and magnetic properties of a chiral one-dimensional molecular-based magnet, Mol. Cryst. Liq. Cryst. 343 (2000) 97-102.

6.      A.S. Markosyan, Y. Hosokoshi, K. Inoue, Influence of the thermal excitations of the ferrimagnetic љlinear trimer on the paramagnetic behavior of the layered metal-radical complex {Mn(hfac)2}3(3RD)2?n-C7H16, Phys. Lett. A 261 (1999) 212-216.

7.      I.S. Dubenko, I.Yu. Gaidukova, Y. Hosokoshi, K. Inoue, A.S. Markosyan, Magnetic phase diagram and pressure effect on the magnetic properties of the Y1‑xGdxMn2 intermetallic compounds, J. Phys.: Condens. Matter 11 (1999) 2937-2953.

8.      I.S. Dubenko, I.V. Golosovsky, A.S. Markosyan, I. Mirebeau, Neutron diffraction study of the magnetic ordering in the Ho(Mn1‑xAlx)2 system, J. Phys.: Condens. Matter 10 (1998) 11755-11764.

9.      R.Z. Levitin, A.S. Markosyan, Effects of magnetic instability in f-d intermetallic compounds, J. Magn. Magn. Mater. 177-181 (1998) 563-568.