Publications (40)
Optical Spectroscopy in CoO: Phonons, Electric, and Magnetic Excitations
Ch. Kant, T. Rudolf, F. Schrettle +5
The reflectivity of single-crystalline CoO has been studied by optical spectroscopy for wave numbers ranging from 100 to 28,000\wn and for temperatures 8 325 K\@. A splitti…
Optical conductivity in multiferroic GaVS and GeVS: Phonons and electronic transitions
S. Reschke, F. Mayr, Zhe Wang +7
We report on optical spectroscopy on the lacunar spinels GaVS and GeVS in the spectral range from 100 to 23000 cm and for temperatures from 5 to 300 K. These…
Electromagnons, magnons, and phonons in EuHoMnO
Zhenyu Chen, M. Schmidt, Zhe Wang +5
Here we present a detailed study of the THz and FIR response of the mixed perovskite manganite system EuHoMnO for holmium concentrations x = 0.1 and 0.3. We compare…
Optical phonons, spin correlations, and spin-phonon coupling in the frustrated pyrochlore magnets CdCr2O4 and ZnCr2O4
Ch. Kant, J. Deisenhofer, T. Rudolf +7
We report on infrared, Raman, magnetic susceptibility, and specific heat measurements on CdCr2O4 and ZnCr2O4 single crystals. We estimate the nearest-neighbor and next-nearest neig…
Electronic and phonon excitations in α-RuCl
S. Reschke, F. Mayr, Zhe Wang +3
We report on THz, infrared reflectivity and transmission experiments for wave numbers from 10 to 8000 cm ( 1 meV - 1 eV) and for temperatures from 5 to 295 K on the Ki…
Optical evidence for symmetry changes above the Neel temperature in KCuF3
J. Deisenhofer, I. Leonov, M. V. Eremin +6
We report on optical measurements of the 1D Heisenberg antiferromagnet KCuF3. The crystal-field excitations of the Cu2+ ions have been observed and their temperature dependence can…
Large and Small Polaron Excitations in La2/3(Sr/Ca)1/3MnO3 Films
Ch. Hartinger, F. Mayr, J. Deisenhofer +2
We present detailed optical measurements of the mid-infrared (MIR) excitations in thin films of La2/3Sr1/3MnO3 (LSMO) and La2/3Ca1/3MnO3 (LCMO) across the magnetic transition. The…
Unusual Non-Fermi Liquid Behavior of CeLaNiGe Analyzed in a Single Impurity Anderson Model with Crystal Field Effects
E. -W. Scheidt, F. Mayr, U. Killer +6
CeNiGe exhibits unusual non-Fermi liquid behavior with the largest ever recorded value of the electronic specific heat JKmol without showi…
Broadband dielectric response of CaCu3Ti4O12: From dc to the electronic transition regime
Ch. Kant, T. Rudolf, F. Mayr +4
We report on phonon properties and electronic transitions in CaCu3Ti4O12, a material which reveals a colossal dielectric constant at room temperature without any ferroelectric tran…
Spin-phonon coupling in ZnCr2Se4
T. Rudolf, Ch. Kant, F. Mayr +3
Spin-phonon coupling and magnetodielectric effects of ZnCr2Se4 were investigated by means of infrared (IR) spectroscopy as a function of temperature and magnetic field. ZnCr2Se4 is…
Possible Localization Behavior of the Inherent Conducting Polymer (CH)ReO
E. --W. Scheidt, R. Miller, Ch. Helbig +5
Polymeric methyltrioxorhenium (poly-MTO) represents the first example of an inherent conducting organometallic oxide. It adopts the structural motives and transport properties of s…
On the room temperature multiferroic BiFeO3: Magnetic, dielectric and thermal properties
Jun Lu, A. Günther, F. Schrettle +7
Magnetic dc susceptibility between 1.5 and 800 K, ac susceptibility and magnetization, thermodynamic properties, temperature dependence of radio and audio-wave dielectric constants…
High-Frequency Electromagnon in GdMnO3
A. Shuvaev, F. Mayr, A. Loidl +2
We present the results of transmittance experiments on GdMnO3 multiferroic manganite in the far infrared frequency range. The spectra allow to obtain the positions and the intensit…
Phonon-Metamorphosis in Ferromagnetic Manganite Films: Probing the Evolution of an Inhomogeneous State
Ch. Hartinger, F. Mayr, A. Loidl +1
The analysis of phonon anomalies provides valuable information about the cooperative dynamics of lattice, spin and charge degrees of freedom. Significant is the anomalous temperatu…
Extremely Small Energy Gap in the Quasi-One-Dimensional Conducting Chain Compound SrNbO
C. A. Kuntscher, S. Schuppler, P. Haas +7
Resistivity, optical, and angle-resolved photoemission experiments reveal unusual one-dimensional electronic properties of highly anisotropic SrNbO. Along the conducting c…
Magnetic-order induced phonon splitting in MnO from far-infrared spectroscopy
T. Rudolf, Ch. Kant, F. Mayr +1
Detailed far-infrared spectra of the optical phonons are reported for antiferromagnetic MnO. Eigenfrequencies, phonon damping and effective plasma frequencies are studied as a func…
Excitations and relaxation dynamics in multiferroic GeV4S8 studied by THz and dielectric spectroscopy
S. Reschke, Zhe Wang, F. Mayr +4
We report on THz time-domain spectroscopy on multiferroic GeV4S8, which undergoes orbital ordering at a Jahn-Teller transition at 30.5 K and exhibits antiferromagnetic order below…
Optical properties of ZnCr2Se4 - Spin-phonon coupling and electronic d-d-like excitations
T. Rudolf, Ch. Kant, F. Mayr +4
We studied the optical properties of antiferromagnetic ZnCr2Se4 by infrared spectroscopy up to 28,000 cm-1 and for temperatures from 5 to 295 K. At the magnetic phase transition at…
Sub-gap optical response across the structural phase transition in van der Waals layered α-RuCl
S. Reschke, F. Mayr, S. Widmann +7
We report magnetic, thermodynamic, thermal expansion, and on detailed optical experiments on the layered compound -RuCl focusing on the THz and sub-gap optical response acr…
Universal exchange-driven phonon splitting in antiferromagnets
Ch. Kant, M. Schmidt, Z. Wang +4
We report a linear dependence of the phonon splitting ÎÏon the non-dominant exchange coupling constant J_{nd} in the antiferromagnetic transition-metal monoxides MnO, FeO, CoO, N…
Coupling of phonons and electromagnons in GdMnO_3
A. Pimenov, T. Rudolf, F. Mayr +3
The infrared and Terahertz properties of GdMnO_3 have been investigated as function of temperature and magnetic field, with special emphasis on the phase boundary between the incom…
Infrared phonons and specific heat in Ba3Cr2O8
Zhe Wang, M. Schmidt, A. Günther +7
We report on the phonon spectrum of Ba3Cr2O8 determined by infrared spectroscopy, and on specific heat measurements across the Jahn-Teller transition in magnetic fields up to 9 T.…
Transport, magnetic, thermodynamic and optical properties in Ti-doped Sr_2RuO_4
K. Pucher, J. Hemberger, F. Mayr +9
We report on electrical resistivity, magnetic susceptibility and magnetization, on heat capacity and optical experiments in single crystals of Sr_2Ru_(1-x)Ti_xO_4. Samples with x=0…
Polar phonons and spin-phonon coupling in HgCr2S4 and CdCr2S4
T. Rudolf, Ch. Kant, F. Mayr +3
Polar phonons of HgCr2S4 and CdCr2S4 are studied by far-infrared spectroscopy as a function of temperature and external magnetic field. Eigenfrequencies, damping constants, effecti…
Lattice dynamics and electronic excitations in a large family of lacunar spinels with a breathing pyrochlore lattice structure
S. Reschke, F. Meggle, F. Mayr +6
Reproducing the electronic structure of AMX lacunar spinels with a breathing pyrochlore lattice is a great theoretical challenge due to the interplay of various factors. Th…
Spin-orbiton and quantum criticality in FeSc2S4
L. Mittelstädt, M. Schmidt, Zhe Wang +7
In FeSc2S4 spin-orbital exchange competes with strong spin-orbit coupling, suppressing long-range spin and orbital order and, hence, this material represents one of the rare exampl…
Far-infrared optical excitations in multiferroic TbMnO_3
M. Schmidt, Ch. Kant, T. Rudolf +5
We provide a detailed study of the reflectivity of multiferroic TbMnO_3 for wave numbers from 40 cm^{-1} to 1000 cm^{-1} and temperatures 5 K < T < 300 K. Excitations are studied f…
Nodal line resonance generating the giant anomalous Hall effect of CoSnS
F. Schilberth, M. -C. Jiang, S. Minami +11
Giant anomalous Hall effect (AHE) and magneto-optical activity can emerge in magnets with topologically non-trivial degeneracies. However, identifying the specific band structure f…
Hydrogen-bond equilibria and life times in a supercooled monohydroxy alcohol
C. Gainaru, S. Kastner, F. Mayr +6
Dielectric loss spectra covering 13 decades in frequency were collected for 2-ethyl-1-hexanol, a monohydroxy alcohol that exhibits a prominent Debye-like relaxation, typical for se…
Wüstite: Electric, thermodynamic and optical properties of FeO
F. Schrettle, Ch. Kant, P. Lunkenheimer +3
We report on a systematic optical investigation of wüstite. In addition, the sample under consideration, Fe0.93O, has been characterized in detail by electrical transport, dielect…
Spin-phonon coupling in antiferromagnetic chromium spinels
T. Rudolf, Ch. Kant, F. Mayr +3
The temperature dependence of eigenfrequencies and intensities of the IR active modes has been investigated for the antiferromagnetic chromium spinel compounds CdCr2O4, ZnCr2O4, Zn…
Phonon anomalies and charge dynamics in Fe_{1-x}Cu_{x}Cr_{2}S_{4} single crystals
T. Rudolf, K. Pucher, F. Mayr +5
A detailed investigation of phonon excitations and charge carrier dynamics in single crystals of Fe_{1-x}Cu_{x}Cr_{2}S_{4} (x = 0, 0.2, 0.4, 0.5) has been performed by using infrar…
Exciton-magnon transitions in the frustrated chromium antiferromagnets CuCrO2, alpha-CaCr2O4, CdCr2O4, and ZnCr2O4
M. Schmidt, Zhe Wang, Ch. Kant +7
We report on optical transmission spectroscopy of the Cr-based frustrated triangular antiferromagnets CuCrO2 and alpha-CaCr2O4, and the spinels CdCr2O4 and ZnCr2O4 in the near-infr…
Orbital fluctuations and orbital order below the Jahn-Teller transition in Sr3Cr2O8
Zhe Wang, M. Schmidt, A. Günther +10
We report on the magnetic and phononic excitation spectrum of Sr3Cr2O8 determined by THz and infrared (IR) spectroscopy, and electron spin resonance (ESR) measurements across the J…
Poly-MTO, {(CH_3)_{0.92} Re O_3}_\infty, a Conducting Two-Dimensional Organometallic Oxide
R. Miller, E. -W. Scheidt, G. Eickerling +7
Polymeric methyltrioxorhenium, {(CH_{3})_{0.92}ReO_{3}}_{\infty} (poly-MTO), is the first member of a new class of organometallic hybrids which adopts the structural pattern and ph…
Evolution of Quantum Criticality in CeNi_{9-x}Cu_xGe_4
L. Peyker, C. Gold, E. -W. Scheidt +7
Crystal structure, specific heat, thermal expansion, magnetic susceptibility and electrical resistivity studies of the heavy fermion system CeNi_{9-x}Cu_xGe_4 (0 <= x <= 1) reveal…
Dynamic conductivity of semiconducting manganites approaching the metal-insulator transition
P. Lunkenheimer, F. Mayr, A. Loidl
We report the frequency-dependent conductivity of the manganite system La1-xSrxMnO3 (x <= 0.2) when approaching the metal-insulator transition from the insulating side. Results fro…
Polaronic excitations in CMR manganite films
Ch. Hartinger, F. Mayr, A. Loidl +1
In the colossal magnetoresistance manganites polarons have been proposed as the charge carrier state which localizes across the metal-insulator transition. The character of the pol…
Cooperative dynamics in doped manganite films: phonon anomalies in the ferromagnetic state
Ch. Hartinger, F. Mayr, A. Loidl +1
We present optical measurements of phononic excitations in LaCaMnO (LCMO) and LaSrMnO (LSMO) thin films covering the full temperature ra…
Spin-driven Phonon Splitting in Bond-frustrated ZnCr2S4
J. Hemberger, T. Rudolf, H. -A. Krug von Nidda +4
Utilizing magnetic susceptibility, specific heat, thermal expansion and IR spectroscopy we provide experimental evidence that the two subsequent antiferromagnetic transitions in Zn…