Group of infrared and millimeter wave spectroscopy

Members of the group:

• Kurnosov V.S., Head of the group, Doctor of Sciences (Physics & Mathematics), Head of the Department;

• Yeremenko A.V., Candidate of Sciences (Ph.D), senior researcher;

• Tsapenko V.V., Candidate of Sciences (Ph.D), engineer.

The main field of research:

• Mechanisms of the influence of magnetic ordering of a medium on the formation of its low-energy excitation spectrum.

• Structural and magnetic phase transitions in multisublattice magnets.

• Optical properties of frustrated magnetic structures.

Equipment:

    Experimental equipment allows to carry out investigation of absorption and reflection spectra in far infrared range of wavelengths. Temperature range extends from room to 4.2 K; magnetic fields are up to 30 kOe. FTIR spectrometer (0.02-0.2 mm) equipped with wide-temperature measurement cell (4.2-300 K) and superconducting solenoid (magnetic field up to 30 kOe).

The most important results:

• Detection of one-phonon light absorption and scattering in crystals induced by the Brillouin zone reduction during magnetic ordering.

• Detection of the phonon mechanism of antistockes excitation of a photoluminescence in CsMnCl₃•2H₂O single crystal with chain-like structure.

• Detection of the resonance interaction between phonon modes from the center and boundary of the paramagnetic Brillouin zone in magnetically ordered phase of CsFeCl₃•2H₂O crystal.

• Detection of the influence of a stripe charge ordering on the formation of spectra of phonons and magnons in low-dimensional nickelates.

• Detection of two-magnon IR absorption in the cubic non-centrosymmetric multi-sublattice Cu₂OSeO₃ ferrimagnet, one of the rare materials with a "skyrmion" magnetic phase.

• Detection in the IR spectra of ferroborates electronic transitions within ground state multiplet of rare earths induced by electron-phonon resonance interaction.