Dresden 2014 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Spin structures and Magnetic Phase Transitions
MA 15.3: Vortrag
Dienstag, 1. April 2014, 10:00–10:15, HSZ 403
Investigation of the Spin-Peierls Transition in TiPO4 — •Patrick Reuvekamp1, Reinhard K. Kremer1, Joseph M. Law2, and Robert Glaum3 — 1Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 2Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 3Rheinische Friedrich-Wilhelms-Universität, Institut für Anorganische Chemie, Bonn, Germany
At room temperature, TiPO4 crystallizes in the orthorhombic CrVO4 structure type characterized by one-dimensional equidistant Ti atoms running along the c-axis. From high temperature magnetic susceptibility measurements, the afm intrachain spin exchange between the Ti3+ (3d1, S = 1/2) cations was observed to be 965 K which is remarkably large for a spin-Peierls (SP) compound.[1] Below room temperature, a two stage SP transition occurs comprising two sequential magnetostructural phase transitions at Tc2 ∼ 110 K and Tc1∼ 74 K into a non-magnetic singlet groundstate. NMR measurements indicated the intermediate phase to be incommensurate.[1] Utilizing low-temperature single-crystal x-ray diffraction and thermal expansion measurements, we investigated in detail the temperature and magnetic field dependence of these two transitions and observed a dimerization of the Ti chains below Tc2. We observed that only the Tc1 transition is dependent on the magnetic field. At 9 T, Tc2 decreases by ∼ −100 mK. The magnetic field dependence of Δ Tc1/Tc1 ∝ H2, consistent with standard SP theory.[1]J. M. Law et al., Phys. Rev. B 83, 180414 (2011). [2]M. Bykov et al., Phys. Rev. B 88, 184420 (2013).