Deutsche Physikalische Gesellschaft e. V. (DPG), 31.3.-4.4.2014

Mo, 15:30 TT 20.3

Spin-lattice coupling in the frustrated S=1/2 compound Cu7Te6O18F2

Vladimir Gnezdilov, Peter Lemmens, Angela Möller, Shichao Hu, Mats Johnsson, IPKM, TU-BS, Braunschweig; ILTPE NAS, Ukraine; Dept. Chem., Univ., Houston, USA; DMEC, Stockholm, Sweden

We present a Raman scattering study of the novel spin-frustrated S=1/2 compound Cu7Te6O18F2. The phonons of this compound display evidence for strong spin-lattice coupling. Furthermore, there exists a broad magnetic scattering continuum that markedly changes with the onset of long-range ordering. Work supported by DFG and B-IGSM.

Mo, 18:15 TT 23.7

Orbital contribution to the spin-Peierls transition in TiPO4

D. Wulferding, A. Moeller, K.-Y. Choi, Yu. Pashkevich; R. Babkin, K. Lamonova, P. Lemmens, J. Law, R. Kremer, R. Glaum, IPKM, TU-BS, Braunschweig, Germany; Dept. Physics, POSTECH, Korea, Dept. Chem., Univ., Houston, USA; Dept. Phys., CA Univ., Seoul, Korea, DonFTI, Donetsk, Ukraine; Dresden HMFL, Dresden, Germany, MPI-FKF, Stuttgart, Germany, IAC, Bonn, Germany

We observe unusual lattice dynamics as well as evidence for an orbital instability preceding the spin-Peierls transition in TiPO4. Furthermore, there exist high energy excitations of mixed electronic and lattice origin that suggest an exotic dimerization process, different from other spin-Peierls materials. Therefore, the energy gain is related to magnetoelastic and orbital contributions.

Di, 15:00 TT 48.5

Excitations of surface and bulk states in spin orbit dominated materials

Peter Lemmens 1, Vladimir Gnezdilov 1,2, Dirk Wulferding 3, Patrik Recher 4, Helmuth Berger 5, Yoichi Ando 6, R. Sankar 7, Fang-Cheng Chou 7, 1 IPKM, TU-BS, Braunschweig; 2 ILTPE, Kharkov, Ukraine; 3 POSTECH, Korea; 4 IMAPH, TU-BS, Braunschweig; 5 EPFL, Lausanne, Switzerland; 6 ISIR, Osaka, Japan; 7 CCMS, National Taiwan Univ., Taipei, Taiwan

Using Raman scattering experiments we probe inelastic processes in the giant Rashba material BiTeI, the topological semimetal Cd3As2 and several topological insulators. By comparing surface with bulk scattering processes we notice the dominance of quantum well states. With exception to Cd3As2 all materials show pronounced resonances in the Raman scattering cross section.

Mi, 11:30 TT 55.2

Spin dynamics in the Haldane compound SrNi2V2O8

Vladimir Gnezdilov, Peter Lemmens, Anup Kumar Bera, ATM Nazmul Islam, Bella Lake; TU-BS, Braunschweig, ILTPE NAS, Ukraine, HZBME, Helmholtz-Zentrum, Berlin

We present a Raman scattering study of the quasi-one-dimensional Haldane chain compound SrNi2V2O8. In contrast to simple expectations, complex temperature-dependent magnetic excitations exist. Our observations provide strong evidence that SrNi2V2O8 is indeed close to the phase boundary that separates a spin-liquid and an Ising-like ordered state on the Sakai-Takahashi phase diagram.