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TT: Fachverband Tiefe Temperaturen
TT 22: CE: Spin Systems and Itinerant Magnets
TT 22.13: Vortrag
Mittwoch, 24. März 2010, 12:45–13:00, H21
Probing spin correlations in the highly frustrated magnets CdCr2O4 and ZnCr2O4 — •Christian Kant1, Joachim Deisenhofer1, Torsten Rudolf1, Franz Mayr1, Florian Schrettle1, Vladimir Tsurkan1,2, and Alois Loidl1 — 1Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg, Germany — 2Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, Republic of Moldova
The spinel systems CdCr2O4 and ZnCr2O4 can be regarded as paradigms for highly frustrated systems where antiferromagnetic nearest-neighbor Heisenberg exchange leads to inherent frustration and considerable degeneracy of the magnetic ground state.
We performed optical, magnetic susceptibility, and specific heat measurements on single crystals of both compounds. From the magnetic susceptibility we estimate the nearest-neighbor and next-nearest neighbor exchange constants. The spin-spin correlation functions is derived from the magnetic susceptibility and the magnetic contribution to the specific heat. Comparing the frequency shift of the infrared optical phonons above TN, we obtain the spin-phonon coupling constant in both systems.