Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 32: Spin Structures and Magnetic Phase Transitions
MA 32.7: Vortrag
Mittwoch, 18. März 2015, 16:45–17:00, EB 202
Hydrostatic Pressure Investigation on the Magnetic and Structural Properties of the Quantum-Spin-Chain CuAs2O4 — •Kevin Caslin1, Reinhard Kremer1, Karl Syassen1, Fereidoon Razavi2, Michael Hanfland3, Mike Whangbo4, and Elijah Gordon4 — 1Max Planck Institute Stuttgart — 2Brock University — 3ESRF — 4North Carolina State University
CuAs2O4 (Trippkeite) is a S =1/2 quantum-spin-chain system with competing ferromagnetic nearest-neighbor (NN) and antiferromagnetic next-nearest-neighbor (NNN) spin-exchange interactions which undergoes long-range ferromagnetic ordering below 7.4 K. We have investigated the pressure dependence of the magnetic and structural properties of the CuAs2O4 by single-crystal synchrotron x-ray diffraction, Raman spectroscopy and SQUID magnetometry under hydrostatic pressure. Precise structural parameters gained from the single crystal x-ray structure determination under hydrostatic pressure have been used for detailed density functional calculations of the spin-exchange interactions. Furthermore, we have correlated the spin-exchange constants to the magnetic properties measured under hydrostatic pressure. Up to approximately 9 GPa we observe a significant reduction of the Jahn-Teller elongations of the distorted CuO6 octahedra. Above approximately 9 GPa a structural phase transition occurs which leads to modifications of the crystals structure driving both NN and NNN spin-exchange constants to the ferromagnetic regime, thus, removing the magnetic frustration.