109 citations · 817 across the 26 of their papers we have counts for
16 papers · 1 filter
Orbiton-mediated multi-phonon scattering in LaSrMnO
K. -Y. Choi, P. Lemmens, G. Güntherodt +6
We report on Raman scattering measurements of single crystalline LaSrMnO (=0, 0.06, 0.09 and 0.125), focusing on the high frequency regime. We observe multi-phon…
Existence of orbital polarons in ferromagnetic insulating LaSrMnO (0.110.14) evidenced by giant phonon softening
K. -Y. Choi, P. Lemmens, G. Güntherodt +6
We present an inelastic light scattering study of single crystalline (LaPr)SrMnO (, and ,). A giant softe…
Quantum phase transition in the dioptase magnetic lattice
C. Gros, P. Lemmens, K. -Y. Choi +3
The study of quantum phase transitions, which are zero-temperature phase transitions between distinct states of matter, is of current interest in research since it allows for a des…
Structural Phase Transition in the 2D Spin Dimer Compound SrCu2(BO3)2
K. Sparta, G. J. Redhammer, P. Roussel +11
A displacive, 2nd order structural phase transition at Ts=395 K from space group I`4 2 m below Ts to I 4/m c m above Ts has been discovered in the two-dimensional spin dimer compou…
Collective Singlet Excitations and Evolution of Raman Spectral Weights in the 2D Spin Dimer Compound SrCu2(BO3)2
Peter Lemmens, M. Grove, M. Fischer +5
We present a Raman light scattering study of the two-dimensional quantum spin system SrCu2(BO3)2 and show that the magnetic excitation spectrum has a rich structure, including seve…
Electron-phonon and spin-phonon coupling in NaVO: charge fluctuations effect
E. Ya. Sherman, M. Fischer, P. Lemmens +2
We show that the asymmetric crystal environment of the V site in the ladder compound NaVO leads to a strong coupling of vanadium 3d electrons to phonons. This coupling…
Quantum Spin Systems: From Spin Gaps to Pseudo Gaps
P. Lemmens, M. Fischer, M. Grove +5
Many low dimensional spin systems with a dimerized or ladder-like antiferromagnetic exchange coupling have a gapped excitation spectrum with magnetic bound states within the spin g…
Spin gap behavior and charge ordering in α^{\prime}-NaV_2O_5 probed by light scattering
M. Fischer, P. Lemmens, G. Els +5
We present a detailed analysis of light scattering experiments performed on the quarter-filled spin ladder compound -NaVO for the temperature range 5 KT$…
Magnetic Bound States in Dimerized Quantum Spin Systems
P. Lemmens, M. Fischer, M. Grove +5
Magnetic bound states are a general phenomenon in low dimensional antiferromagnets with gapped singlet states. Using Raman scattering on three compounds as dedicated examples we sh…
Revival of the spin-Peierls transition in Cu_xZn_(1-x)GeO_3 under pressure
M. Fischer, P. H. M. van Loosdrecht, P. Lemmens +8
Pressure and temperature dependent susceptibility and Raman scattering experiments on single crystalline Cu_xZn_(1-x)GeO_3 have shown an unusually strong increase of the spin-Peier…
Observation of three-magnon light scattering in CuGeO_3
G. Els, P. H. M. van Loosdrecht, P. Lemmens +7
Temperature and magnetic field dependent polarized Brillouin spectra of CuGeO_3 are reported. In addition to a bound singlet state at 30 cm^{-1}, a new feature has been observed at…
Effects of in-chain and off-chain substitutions on spin fluctuations in the spin-Peierls compound CuGeO_3
P. Lemmens, M. Fischer, G. Güntherodt +6
The effect of in-chain and off-chain substitutions on 1D spin fluctuations in the spin-Peierls compound CuGeO_3 has been studied using Raman scattering in order to understand the i…
Experimental evidence for a spin-Peierls-transition in
M. Weiden, R. Hauptmann, C. Geibel +4
We present the first measurements of magnetisation and Raman light scattering on single crystals. Below 34 K, we observe a pronounced isotropic decrease of the suscep…
Magnon-magnon interactions in the Spin-Peierls compound CuGeO_3
C. Gros, W. Wenzel, A. Fledderjohann +6
In a magnetic substance the gap in the Raman spectrum, Delta_R, is approximatively twice the value of the neutron scattering gap, Delta_S, if the the magnetic excitations (magnons)…
Substitution effects on spin fluctuations in the spin-Peierls compound CuGeO_3
M. Fischer, P. Lemmens, G. Güntherodt +4
Using Raman scattering we studied the effect of substitutions on 1D spin fluctuations in CuGeO_3 observed as a spinon continuum in frustration induced exchange scattering. For temp…
The J_1-J_2 model revisited : Phenomenology of CuGeO_3
V. N. Muthukumar, Claudius Gros, Roser Valenti +6
We present a mean field solution of the antiferromagnetic Heisenberg chain with nearest (J_1) and next to nearest neighbor (J_2) interactions. This solution provides a way to estim…