Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 44: Poster Session Correlated Electrons

TT 44.75: Poster

Donnerstag, 17. März 2011, 10:00–13:00, P1

Collective orbital excitations in GdVO₃ — •Michael Voigt¹, Luis Mäder¹, Konstantin Shportko¹, Graeme R. Blake², Nandang Mufti², Agustinus A. Nugroho^2,3, Thomas T. M. Palstra², and Markus Grüninger¹ — ¹Universität zu Köln — ²University of Groningen — ³Institut Teknologi Bandung

In the vanadates (RVO₃) orbital interactions are expected to be especially strong. In the compounds YVO₃ and HoVO₃ these interactions lead to two different phases of orbital ordering (OO), one in an intermediate temperature range with G-type OO and one low-temperature phase with C-type OO. [1] In these orbitally ordered states, one expects novel collective excitations, so called orbitons, which are analogous to spin waves in a magnetically ordered state.

Previous optical measurements of YVO₃ and HoVO₃ have shown a striking feature at 0.4 eV with polarization E∥ c in the intermediate phase which is interpreted as bi-orbiton excitation. [2] Furthermore a second interesting feature at 0.55 eV with polarization E∥ a is observed. The interpretation of this feature is still a puzzle.

We show the optical conductivity σ(ω) of GdVO₃ single crystals for the mid-infrared range and temperatures from 10 K to 300 K. In GdVO₃, G-type OO (the intermediate phase of YVO₃) extends down to the lowest temperatures, offering additional information on the excitations discussed above.
Blake et al., PRB 79, 045101 (2009)
Benckiser et al., NJP 10, 053027 (2008)