Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 17: Correlated Electrons: Spin Systems, Itinerant Magnets 2

TT 17.8: Vortrag

Montag, 11. März 2013, 17:15–17:30, H19

Investigation of Ferromagnetic Copper Oxides — •Kevin Caslin¹, Reinhard Kremer¹, Mike Whangbo², Jia Liu², and Franz Pertlik³ — ¹MPI für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — ²Dept. of Chemistry, North Carolina State Univ., Raleigh, North Carolina 27695-8204, USA — ³Inst. f. Mineralogie und Kristallographie d. Univ., A-1010 Wien, Österreich

We are investigating low dimensional S=1/2 Cu quantum-chain systems. Materials containing Cu S=1/2 moments in a distorted oxygen octahedral environment form CuO₂ ribbon chains. Such ribbon chains support ferromagnetic (FM) nearest-neighbour (NN) via Cu-O-Cu exchange and antiferromagnetic (AFM) next-nearest-neighbour (NNN) via Cu-O-O-Cu exchange. Often the NNN-AFM interaction is dominant and leads to a low temperature, AFM, long-range ordering. Systems of this type are known to develop unusual structural distortions and incommensurate spiral magnetic structures.[1,2,3] In this study, we search for S=1/2 Cu based materials with crystal structures leading to a predominate NN-FM exchange. X-ray diffraction, heat capacity, thermal expansion and magnetic measurements were performed to characterize such materials. DFT and band structure calculations were also carried out for further invesitgation.
[1] B. J. Gibson, R. K. Kremer, A. V. Prokofiev, W. Assmus, and G. J. McIntyre, Physica B 350, E253 (2004)
C. Lee, Jia Liu, M.-H Whangbo, H.-J. Koo, R. K. Kremer, and A. Simon, Phys. Rev. B 86, 060407 (2012)
M. G. Banks, R. K. Kremer, C. Hoch, A. Simon, B. Ouladdiaf, J.-M. Broto, H. Rakoto, C. Lee, and M.-H. Whangbo, Phys. Rev. B 80, 024404 (2009)