DPG Phi
Verhandlungen
Verhandlungen
DPG

Dresden 2006 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.117: Poster

Wednesday, March 29, 2006, 14:30–18:30, P1

Temperature- and doping-induced spin-state transitions of RCoO3 — •K. Berggold, N. Hollmann, M. Reuther, M. Kriener, J. Baier, C. Zobel, A. Reichl, and T. Lorenz — II. Physikalisches Institut, University of Cologne, Germany

LaCoO3 attracts a lot of attention, because it undergoes a temperature-induced spin-state transition. There are different ways to tune this spin-state transition, either to stabilize the low-spin state by replacing La with smaller rare earth ions R, or to suppress it by the introduction of charge-carriers[1,2]. For low doping levels so-called high-spin polarons are formed. We studied the thermal conductivity κ on RCoO3 single crystals with R = La, Pr, Nd, and Eu, as well as on La1−xSrxCoO3 with 0≤ x≤0.3 and find that κ is strongly suppressed by the spin-state transition. Particularly we present magnetic-field dependent measurements for low temperatures to investigate the influence of the high-spin polarons to κ. A low thermal conductivity is one pre-condition to reach large values of the thermoelectric figure of merit ZT, which is necessary for thermoelectric applications. We observe a ZT(max)≈0.03, which is rather high for oxides[3]. We also present first measurements of Eu1−xSrxCoO3. Here, charge-carrier doping should act differently because of the stabilized low-spin state.

[1] Baier et al., PRB 72, 155116 (2005)

[2] Kriener et al.,PRB 69, 094417 (2004)

[3] Berggold et al.,PRB 71, 014443 (2005)

This work was supported by the DFG through SFB 608

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2006 > Dresden