Department of Magnetism

Group for optical and magnetic resonance spectroscopy and pulse magnetic field studies



Members of the group:

  • Kutko K.V., Head of the group, Candidate of Sciences (Ph.D), researcher;

  • Nesterenko N.M., Candidate of Sciences (Ph.D), researcher.

  • Savytskyi V.M., Candidate of Sciences (Ph.D), researcher.

  • Khrustalyov V.M., Candidate of Sciences (Ph.D), junior researcher;


The main field of research:


  • THz spectroscopic studies of magnetic-field-induced lattice changes in highly anisotropic magnetoelastic rare-earth compounds.

  • Phenomenological and symmetry analysis of spontaneous and magnetic field-induced low-temperature Jahn-Teller phase transitions in layered trigonal and orthorhombic crystals.

  • Magnetic resonance properties of low-dimensional magnets, nano- and metal-organic systems.

  • Low temperature studies of magnetic field induced spin-orientational phase transitions in antiferromagnets with strong magnetic anisotropy.

  • Experimental studies of magnetic and electric properties of multiferroic compounds under high pulsed magnetic field.


Equipment:


  • Magnetic resonance spectrometer with a resonator cavity of the appropriate frequency region 1 – 2.5 cm-1 (30 – 75 GHz), superconducting solenoid with a maximum of magnetic field 5 T, temperature interval 2 – 30 K.

  • The pulse magnet with field strenght up to 300 kOe within the hole diameter 27 mm (copper wired multilayer coil with liquid nitrogen cooling) for magnetization (differential magnetic susceptibility) and magnetoelectric effect measurements. Magnetic field pulse diration 30 ms. Sample temperature intervals: 1,6-4,2 ت (liquid helium), 14-20,4 ت (liquid hydrogen).

  • DC superconducting magnet with field up to 6 ز for magnetization and magnetic susceptibility measurement in the tempereture interval 1.6 - 300 K.

  • DC water-cooled magnet with field up to 1.5 T for magnetic properties measurements at room and helium temperatures.


The most important results:


  • By time-domain spectroscopy studies of the dielectric material KY(MoO4)2, the re-emission of monochromatic sub-THz radiation by coherent optical infrared-active phonons has been found. The remarkably long decay time together with the chemical stability of the employed material suggests a variety of possible applications in THz technology. (Adv. Science, 12, 2, 202407028, 2025)

  • An exceptionally strong magnetostriction has been observed in the layered paramagnetic compound KEr(MoO4)2. The microscopic mechanism of magnetostriction has been determined by the magnetic-field-induced lattice distortion, which is driven by changes in the quadrupole moments of the Er3+ ion. (Adv. Electron. Mater, 8, 3, 2100770, 2022).

  • Using Raman and far-infrared spectroscopies, spontaneous ordering of the Jahn-Teller type in the rare-earth-based system KDy(MoO4)2 has been observed. It was shown, that the ordering of quadrupoles in the electron subsystem is accompanied with the appearance of energy nonequivalent distortions of rare-earth ions in the ordered phase. A mean-field theory explaining the onset of a type of ordering has been constructed, which can be applied to describe the phase transitions of the Jahn-Teller type in the whole class of the rhombic crystals. (Phys. Rev. B 98, 064406, 2018).

  • Far-infrared transmission spectra of the layered double molybdates KY(MoO4)2, KDy(MoO4)2, KEr(MoO4)2, and KTm(MoO4)2 have been obtained. It has shown that the low-energy lattice vibrations in these compounds are well described by a quasi-one-dimensional microscopic model, which was developed to explain the dispersion of shear vibrational modes across the Brillouin zone in layered crystals. (Journal of Physics: Condensed Matter, 29, 095402, 2017)

  • It has been found that the high-field phase in the antiferromagnetic LiCoPO4 in the magnetic field range 21–28.5 T is noncentrosymmetric and exhibits a magnetoelectric response. (H,T) phase diagrams of LiCoPO4 have been constructed in magnetic fields up to 285 kOe. (Low Temp. Phys. 42, 280, 2016; Low Temp. Phys. 43, 1332, 2017).

  • A new high-field phase of LiCoPO4 has been found in the magnetic field range of 21–28.5 T, and it has been shown that the transition from the antiferromagnetic to the saturated paramagnetic state proceeds via three phase transitions. Possible magnetic structures are proposed within a simplified 2D collinear model. (Low Temp. Phys. 36, 558, 2010).

  • Five phase transitions in LiNiPO4 have been found during pulsed magnetization in magnetic fields up to 285 kOe. Using this data, the (H,T) phase diagram in fields up to 285 kOe and temperature range 1.6K – 21K have been constructed. (Czech. J. Phys. 54 (Suppl. 4), 27, 2004).


International cooperation:


  • Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Germany;

  • High Field Magnet Laboratory, Radboud University, Nijmegen, The Netherlands;

  • Molecular Photoscience Research Center, Kobe University, Japan;

  • Department of Condensed Matter Physics, Institute of Physics, Faculty of Science, Univerzita Pavla Jozefa Safarika, Kosice, Slovak Republic.