Hamburg 2001 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 6: Postersitzung I: Josephsonkontakte und SQUIDs, Supraleitung: Theorie, Korrelierte Elektronen, Niederdimensionale Systeme, Magnetotransport, Quantenhalleffekt, Kohlenstoff-Nanoröhrchen, Quantenflüssigkeiten
TT 6.68: Poster
Montag, 26. März 2001, 14:30–17:00, Rang S\ 3
Heat Capacity Studies of the Linear Chain Cuprates LiCuVO4 and α-CuV2O6 — •R.K. Kremer1, A. Prokofiev2, C. Gross2, and W. Aßmus2 — 1MPI für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany — 2Physikalisches Institut der Universität Frankfurt,Robert - Mayer - Straße 2-4, 60325 Frankfurt
The heat capacity of crystals of the two linear chain cuprates LiCuVO4 and α-CuV2O6 has been studied from 1.8 to 200 K and in magnetic fields up to 9 Tesla. LiCuVO4 crystallizes in the SG Imma with edge sharing (Jahn-Teller) distorted Cu-O octahedra propagating along [010]. This arrangement is very similar to that found in the inorganic spin-Peierls compound CuGeO3.
LiCuVO4 and α-CuV2O6 show pronounced one-dimensional magnetic behavior with characteristic broad maxima in the susceptibility due to short range antiferromagnetic correlations at 27 K and at 44 for LiCuVO4 and α-CuV2O6, respectively. The heat capacity of LiCuVO4 reveals an anomaly at 2.34(5) K marking the onset of long-range magnetic ordering. This anomaly removes only about 10 % of the entropy expected for a S=1/2 system. The majority of the entropy is contained in a broad Schottky anomaly extending up to temperatures beyond 50 K. Applying a magnetic field along [100] decreases the ordering temperature rapidly below the accessible temperature range.
Signalized by a sharp anomaly in the heat capacity, α-CuV2O6 undergoes long range magnetic ordering at 22.7(1) K in very good agreement with the results of an AFMR and a recent powder neutron diffraction study.