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MA: Fachverband Magnetismus
MA 14: Cooperative Phenomena: Spin Structures and Magnetic Phase Transitions
MA 14.9: Vortrag
Dienstag, 6. September 2022, 11:45–12:00, H47
Spin structure of Frenkel excitons on Cu2+-ions in the antiferromagnet CuB2O4 revealed by magneto-absorption spectroscopy — •Dennis Kudlacik1, Natalia E. Kopteva1, Dimitri R. Yakovlev1, Mikhail V. Eremin3, Alexey R. Nurmukhametov3, Manfred Bayer1, and Roman V. Pisarev2 — 1Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany — 2St. Petersburg, Russia — 3Kazan, Russia
Frenkel excitons in magnetic insulators have attracted considerable interest in recent years as they allow the migration or transmission of a localized excitation. We have investigated this property which is reflected in the Davydov splitting of the exciton in the antiferromagnet copper metaborate, CuB2O4 [1]. This magnetic insulator consists of two weakly interacting sublattices of Cu2+ ions. Below the Neel temperature of TN=21 K its magnetic structure is dominated by the antiferromagnetic order of the 4b sublattice which comprises 4 Cu2+ ions twice degenerate in spin resulting in the formation of 8 collective charge-spin Frenkel-Davydov excitations. From a comparison of the experimental data with the results of the theoretical model we define the parameters of Frenkel exciton states, determine the electron-energy transfer between antiferromagnetically coupled copper spins as well as the anisotropic Cu2+ g-factors of ground and excited states.
[1] N. E. Kopteva et al., Phys. Rev. B 105, 024421 (2022).