Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Spin structures and Magnetic Phase Transitions

MA 15.6: Vortrag

Dienstag, 1. April 2014, 10:45–11:00, HSZ 403

Absorption and photoluminescence spectroscopy on copper metaborate CuB₂O₄ — •Dennis Kudlacik¹, J. Debus¹, R. V. Pisarev², D. Dunker¹, D. R. Yakovlev^1,2, and M. Bayer¹ — ¹Experimentelle Physik 2, Technische Universität Dortmund, 44227 Dortmund, Germany — ²Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia

CuB₂O₄ contains two nonequivalent Cu²⁺ sublattices, each with different magnetic ordering. The magnetic structure is dominated by the antiferromagnetic order of the 4b sublattice. Interactions may transfer it to the 8d sublattice where it shall coexist with a paramagnetic component. Three different magnetic phase transitions can be observed below 21 K.^[1] Accordingly, it is an ideal candidate to probe magnetic interactions between both sublattices as a function of temperature and, for example, optical excitation. We have studied linear-polarized absorption spectra, magneto-photoluminescence (PL) and photoluminescence excitation (PLE) of CuB₂O₄. The absorption and PL spectra show a rich fine structure containing up to six zero phonon lines. We compare the intensities of the zero phonon lines and magnon related emission lines for the different states of magnetic ordering. Also, the PLE spectroscopy reveals the coupling between the 8d and 4b sublattices. On the whole, the applied optical techniques grant access to crystallographic and magnetic properties of CuB₂O₄.

[1] R.V. Pisarev et al., Phys. Rev. Lett. 93, 037204 (2004).