Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 24: Postersitzung III: Korrelierte Elektronen, ”Orbital Physics”
TT 24.52: Poster
Mittwoch, 10. März 2004, 14:30–19:00, Poster A
Electron Spin Resonance in charge and orbitally ordered manganites — •J. Deisenhofer1, H.-A. Krug von Nidda1, A. Loidl1, T. Nakajima2, and Y. Ueda2 — 1EP V, Center for Electronic Correlations and Magnetism, Institute for Physics, Augsburg University, D-86135 — 2Material Design and Characterization Laboratory,Institute for Solid State Physics, University of Tokyo, 5-1-5
Both the paramagnetic and the magnetically ordered regime have been investigated for La1−xSrxMnO3 (0≤ x≤ 0.2) single crystals by ESR: For x=0.05 the analysis of the temperature dependence and the anisotropy of ESR linewidth and g-value in the orbitally ordered phase allows to determine unambiguously the orbital mixing parameter above TN, indicating that also in pure LaMnO3 orbital ordering is stabilized to a large extent by superexchange processes in the ferromagnetic bonds. For 0.075≤ x < 0.15 we observe anisotropic quasi-ferromagnetic resonance signals persisting far into the paramagnetic regime, indicating the existence of a Griffiths-like phase above long-range magnetic order on crossing from the canted antiferromagnetic state at x=0.075 to a purely ferromagnetic ground state at x=0.175. Moreover, we report on correlations between the ESR linewidth and resistivity at the charge-ordering transition in the layered manganites RBaMn2O6 (R=Y,Dy).