Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 30: Postersitzung IV: Kritische Ph
änomene, Quantenstörstellen, niederdimensionale Systeme
TT 30.23: Poster
Donnerstag, 11. März 2004, 14:30–19:00, Poster A
Thermal conductivity of the layered cuprates R2CuO4 with R = Pr, Nd, Sm, Eu and Gd — •H. Anapa1, K. Berggold1, K. Kordonis1, M. Kriener1, J. Baier1, T. Lorenz1, A. Freimuth1, and S. Barilo2 — 1II. Physikalisches Institut, Universität zu Köln, 50937 Köln — 2Inst. of Sol. St. & Semicond. Phys., National Academy of Sciences, Minsk
La2CuO4, well known as parent compound for high temperature superconductors, is an anti-ferromagnetic insulator with a large exchange constant J≈1400 K. The thermal conductivity shows an unusual double peak structure for a heat current in the Cu-O planes, whereas perpendicular to the planes only one low-temperature maximum is present. It was proposed [1], that this double-peak structure is caused by a structural instability. However, we found this feature also in the related compound SrCuO2Cl2, which has no structural instability, and concluded, that the second maximum arises from additional heat transport by magnetic excitations [2]. To investigate, whether magnetic heat transport is a common feature of single-layer cuprates, we performed thermal conductivity measurements on R2CuO4 with R=Pr, Nd, Sm, Eu and Gd. A structural instability occurs only for R=Eu, Gd, but all R2CuO4 samples show a high-temperature maximum (shoulder) of the in-plane thermal conductivity. This is further evidence, that considerable magnetic heat transport is an intrinsic feature of these cuprates.
[1] J. L. Cohn et al., Phys. Rev. B 52, R13134 (1995)
[2] M. Hofmann et al., Phys. Rev. B 67, 184502 (2003).