Deutsche
Physikalische Gesellschaft e. V. (DPG)
TT 4.1: Vortrag, Montag, 20. März 2017, 09:30–09:45, HSZ 204
Magnetic excitations in the symmetry protected, topological Haldane phase
of SrNi2V2O8
— Vladimir Gnezdilov1,2,
Vladimir Kurnosov2, •Peter
Lemmens1, A. K. Bera3,
A. T. M. N. Islam3, and
Bella Lake3 — 1TU-BS,
Braunschweig — 2ILTP Kharkov — 3HZB Berlin
We report results of a single-crystal Raman scattering study of the coupled
spin-1 Haldane chain compound SrNi2V2O8. In
addition to the one-and two-magnon excitations, broad gapless and temperature
dependent continua are detected with light polarization parallel to the basal
plane. This feature is discussed in terms of spinon-like excitations related to
a symmetry protected topological state, of which the Haldane phase in 1D is a
preeminent example. Work supported by RTG-DFG 1952/1, Metrology for Complex
Nanosystems and the Laboratory for Emerging Nanometrology, TU Braunschweig.
___________________________________________________________________________________________
TT 42.4: Vortrag, Mittwoch, 22. März 2017, 10:15–10:30, HSZ 304
Spectroscopic investigations of a novel Iridate - a possible reference
material for Kitaev physics — Philipp
Benrath1, Angela Möller1,
Vladimir Gnezdilov2,3,
and •Peter Lemmens2 —
1IAC-AC, JGU Mainz — 2TU-BS, Braunschweig — 3ILTP,
Kharvov
In Na2Ir(OH)6 there exist a D3d point group symmetry
with an uniaxial threefold symmetry of the iridium complex. In our search for
nonabelian anyons (fractionalized excitations)[1] we performed a systematic
Raman scattering investigation of its excitation spectrum. Evidence for a
symmetry reduction and its relation to other distorted Kitaev materials are
discussed. Work supported by RTG-DFG 1952/1, the Laboratory for Emerging
Nanometrology, TU Braunschweig, and NTH Contacs in Nanosystems.
[1] A. Glamazda, P. Lemmens, S.-H. Do, K.-Y. Choi, Nature Commun. 7, 12286
(2016).
___________________________________________________________________________________________
TT 42.11: Vortrag, Mittwoch, 22. März 2017, 12:15–12:30, HSZ 304
Effect of symmetry and local distortions on fractionalized excitations in
Kitaev Systems — •Peter Lemmens1,
Vladimir Gnezdilov1,2,
Alexander Glamazda1,2,3,
S.-H. Do3,
K.-Y. Choi3,
Angela Möller4,
Friedrich Freund5, and
Philipp Gegenwart5 —
1TU-BS Braunschweig — 2ILTP Kharkov — 3CAU
Seoul — 4IAC-AC, JGU Mainz — 5EP-VI, ZEKM, Augsburg
In Kitaev physics the role of symmetry is crucial. A prerequisite of the
Kitaev model demands uniaxial threefold symmetry of the iridium complex. [1,2]
Therefore, the comparison of different systems representing the Kitatev model on
different honeycomb-like lattices [3] is an important topic. We performed Raman
scattering investigations on the continuum of fractionalized excitations to
understand the role of symmetry, local distortions and dimensionality. In
detail, we will report on data of α-RuCl3 as well as 2D/3D (Na,Li)2IrO3
and related compounds. Work supported by RTG-DFG 1952/1, the Laboratory for
Emerging Nanometrology, TU Braunschweig, and NTH Contacs in Nanosystems.
[1] G. Jackeli and G. Khaliullin, Phys. Rev. Lett. 102, 017205 (2009); [2] M.
Becker, M. Hermanns, B. Bauer, M. Garst and S. Trebst, Phys. Rev. B 91, 155135
(2015); [3] A. Glamazda, P. Lemmens, S.-H. Do, K.-Y. Choi, Nature Commun. 7,
12286 (2016).
___________________________________________________________________________________________
MA 44.8: Vortrag, Mittwoch, 22. März 2017, 17:00–17:15, HSZ 403
Spectroscopic investigation of a spin liquid (RVB) state and local
distortions in the frustrated spin-1/2 Copper Carbodiimide (CuNCN) —
Azat Sharafeev1,
Vladimir Gnezdilov2, •Peter
Lemmens1, Xiaohui Liu3,
Andrei Tchougreeff3, and
Richard Dronskowski3 —
1TU-BS, Braunschweig — 2ILTP, Kharkov — 3RWTH
Aachen
In CuNCN there exist corrugated layers of Cu2+ bridged by NCN2- groups with a
square planar Cu2+ coordination. Based on very large AF exchange and frustration
a nonmagnetic ground state is observed. On the other side, some evidence for
hidden magnetic order with strong fluctuations typical for low dimensionality
has been given. We critically discuss the presently known scenarios on the basis
of Raman scattering data, giving evidence for local lattice distortions for
T<60K as well as high energy excitations. Work supported by RTG-DFG 1952/1, the
Laboratory for Emerging Nanometrology, TU Braunschweig, and NTH Contacs in
Nanosystems.
APS March Meeting 2017
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session K24: Spectroscopic Signatures of
Fractionalized Excitations in Quantum Magnets
8:00 AM–11:00 AM, Wednesday, March 15, 2017
Room: New Orleans Theater C
Sponsoring Units: DCMP GMAG
Chair:
Ioannis Rousochatzakis, University of Minnesota
Abstract: K24.00005 : Fractionalized
Excitations in higher dimensional Iridates
10:24 AM–11:00 AM
Author: Peter
Lemmens, Inst. Condensed Matter Physics, TU Braunschweig, Germany and Lab.
for Emerging Nanometrology (LENA), TU Braunschweig, Germany
Fractionalization of elementary excitations
remains an excotic phenomenon usually limited to 1D and 2D systems. Here we
report spectroscopic signatures of fractional excitations in the 3D
harmonic-honeycomb iridates beta - and gamma-LiIrO[1]. Our experimental
evidence is based on Raman spectroscopic investigations of the polarization
and temperature dependence of a scattering continuum, a comparison with
earlier investigations of alpha-RuCl[2], and a comparison with theoretical
modelling of the Kitatev model on different topologies [3]. [1] A. Glamazda,
P. Lemmens, S.-H. Do, K.-Y. Choi, Nature Commun. 7, 12286 (2016). [2] L. J.
Sandilands, Y. Tian, K. W. Plumb, Y. -J. Kim, and K. S. Burch, PRL 114,
147201 (2015). [3] J. Knolle, G.-W. Chern, D. L. Kovrizhin, R. Moessner, and
N. B. Perkins, PRL 113, 187201 (2014). B. Perreault, J. Knolle, N. B.
Perkins, and F. J. Burnell, PRB 92, 094439 (2015).