Coherent source submillimeter wave spectroscopy

Козлов, Г. В.; Волков, А. А.

doi:10.1007/bfb0103420

Cited by 167 publications

(71 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The dynamic experiments in the frequency range 0.1 < ν < 1.2 THz were performed in transmittance experiments using a Mach-Zehnder interferometer 19 . This arrangement allowed the investigation of the transmittance and phase shift of the plane-parallel samples as a function of frequency, temperature and external magnetic field.…”

Section: Methodsmentioning

confidence: 99%

Possible evidence for electromagnons in multiferroic manganites

et al. 2006

View full text Add to dashboard Cite

M agnetodielectric materials are characterized by a strong coupling of the magnetic and dielectric properties and, in rare cases, simultaneously show both magnetic and polar order. Among other multiferroics, TbMnO 3 and GdMnO 3 reveal a strong magneto-dielectric coupling and as a consequence fundamentally different spin excitations exist: electro-active magnons (or electromagnons), spin waves that can be excited by a.c. electric fields. Here we provide evidence that these excitations appear in the phase with an incommensurate magnetic structure of the manganese spins. In external magnetic fields this incommensurate structure can be suppressed and the electromagnons wiped out, thereby inducing considerable changes in the index of refraction from d.c. up to terahertz frequencies. Hence, besides adding a creature to the zoo of fundamental excitations, the refractive index can be tuned by moderate magnetic fields, which enables the design of the next generation of optical switches and optoelectronic devices.Enormous progress has been made in the field of multiferroics and the discovery of new classes of ferroelectromagnets (FEMs) with the simultaneous occurrence of magnetic and polar order [1][2][3][4][5] has triggered a revival 6,7 of this old field of magneto-dielectric effects and the electrodynamics of multiferroic media 8 . As well as promising applications of FEMs in the field of modern electronics, for example, as multiple-state memory devices with mutual magnetic or electric control or as magnetically switchable optical devices, fascinating new problems can be tackled in basic research, such as the search for magneto-dielectric excitations.

show abstract

Section: Methodsmentioning

confidence: 99%

Possible evidence for electromagnons in multiferroic manganites

et al. 2006

View full text Add to dashboard Cite

show abstract

“…The dynamic experiments for frequencies 4 cm −1 Ͻ Ͻ 40 cm −1 were carried out in a Mach-Zehnder interferometer arrangement, 33 which allows both: the measurements of the transmittance and the phase shift of a plane-parallel sample. The complex transmission coefficient has been analyzed using the Fresnel optical formulas for transmittance T = ͉t͉ 2 of a plane-parallel sample: 34,35 …”

Section: Methodsmentioning

confidence: 99%

Terahertz conductivity at the Verwey transition in magnetite

et al. 2005

View full text Add to dashboard Cite

The complex conductivity at the (Verwey) metal-insulator transition in Fe3O4 has been investigated at THz and infrared frequencies. In the insulating state, both the dynamic conductivity and the dielectric constant reveal a power-law frequency dependence, the characteristic feature of hopping conduction of localized charge carriers. The hopping process is limited to low frequencies only, and a cutoff frequency ν1 ≃ 8 meV must be introduced for a self-consistent description. On heating through the Verwey transition the low-frequency dielectric constant abruptly decreases and becomes negative. Together with the conductivity spectra this indicates a formation of a narrow Drude-peak with a characteristic scattering rate of about 5 meV containing only a small fraction of the available charge carriers. The spectra can be explained assuming the transformation of the spectral weight from the hopping process to the free-carrier conductivity. These results support an interpretation of Verwey transition in magnetite as an insulator-semiconductor transition with structure-induced changes in activation energy.

show abstract

“…Highfield ESR was performed at a frequency of 185 GHz using a quasi optical technique with backward-wave oscillators as coherent sources for submillimeter wavelength radiation. 9,10 The spectrometer is equipped with a superconducting split-coil magnet with a maximum field of 8T.…”

Section: Sample Preparation and Experimental Detailsmentioning

confidence: 99%

Structural and magnetic dimers in the spin-gapped systemCuTe2O5

et al. 2006

View full text Add to dashboard Cite

We investigated the magnetic properties of the system CuTe2O5 by susceptibility and electron spin resonance measurements. The anisotropy of the effective g-factors and the ESR linewidth indicates that the anticipated structural dimer does not correspond to the singlet-forming magnetic dimer. Moreover, the spin susceptibility of CuTe2O5 can only be described by taking into account interdimer interactions of the same order of magnitude than the intradimer coupling. Analyzing the exchange couplings in the system we identify the strongest magnetic coupling between two Cu ions to be mediated by super-super exchange interaction via a bridging Te ligand, while the superexchange coupling between the Cu ions of the structural dimer only results in the second strongest coupling.

show abstract

Coherent source submillimeter wave spectroscopy

Cited by 167 publications

References 25 publications

Possible evidence for electromagnons in multiferroic manganites

Possible evidence for electromagnons in multiferroic manganites

Terahertz conductivity at the Verwey transition in magnetite

Structural and magnetic dimers in the spin-gapped systemCuTe2O5

Contact Info

Product

Resources

About