Terahertz–infrared electrodynamics of overdoped manganites La.sub.1-x./sub.Ca.sub.x./sub.MnO.sub.3./sub

0439482 - FZÚ 2015 RIV GB eng J - Journal Article
Kadyrov, L.S. - Gorshunov, B.P. - Zhukova, E.S. - Torgashev, V. I. - Prokhorov, A. S. - Motovilova, E.A. - Fischgrabe, F. - Moshnyaga, V.T. - Zhang, T. - Kremer, R. K. - Pracht, U. - Zapf, S. - Pokorný, Jan - Untereiner, G. - Kamba, Stanislav - Dressel, M.
Terahertz–infrared electrodynamics of overdoped manganites La_1-xCa_xMnO₃
Phase Transitions. Roč. 87, 10-11 (2014), s. 1050-1059. ISSN 0141-1594. E-ISSN 1029-0338
Institutional support: RVO:68378271
Keywords : manganites * terahertz
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 0.954, year: 2014

We have measured low-temperature terahertz and infrared spectra of La1–xCa xMnO3 with x = 0.5; 0.6; 2/3, 0.7; 3/4, 0.85; 0.9; 0.95; 0.98 and x = 1 in the form of ceramics and epitaxial films. In the charge-ordered state for commensurate dopings (x = 2/3 and 3/4), we observed an absorption band at frequencies corresponding to the position of the lowest energy van Hove singularity in the folded Brillouin zone. The band is assigned to the boson peak. We observed qualitatively the same boson peak in Raman spectra of La1/3Ca2/3MnO3 ceramics. In antiferromagnetic phase, for the 0.5 ≤ x < 0.85 range of doping, the conductivity mechanism gradually changes from a hopping-like transport at low temperatures to the Drude behavior at elevated temperatures in the paramagnetic phase. For 0.85 ≤ x < 1 (canted antiferromagnetic phase), the electrons behave as Drude-like carriers in the whole temperature interval 5–300 K.
Permanent Link: http://hdl.handle.net/11104/0242773