M. Banville

The interaction of the two-dimensional plasmon with the surface plasmons in an MOS structure

Abstract The two-dimensional electron gas in the inversion layer of an MOS structure gives rise to a two-dimensional plasmon, which has not yet been observed. The interaction of this collective oscillation with the surface plasmons of the semi-metallic film in an MOS structure is calculated in the long wavelength limit. The results indicate large coupling with the tangential surface plasmon and suggest an indirect means of observing the two-dimensional plasmon.

Interaction of interface plasmons and longitudinal optical phonons in a multilayer structure

Abstract The interaction between two-dimensional interface plasmons and longitudinal optical phonons in multilayer structures is analysed in this communication. The dispersion relations for the mixed modes are obtained for periodic boundary conditions in the direction normal to the layer planes. The energy gap between the two bands of mixed modes can be seen in the density of states ϱ k (ω) at fixed k parallel to the layers. ϱ k (ω) also exhibits singularities at the band edges characteristics of the one-dimensional periodic array of parallel layers.

Infrared reflectance of CsNiF3

Abstract We present and analyze the infrared reflectance spectra of CsNiF 3 (2L polytype) as a function of temperature. The parameters of two phonons ( E ∥ c ) and three phonons for ( E ⊥ c ) are determined. Defect related infrared peaks are observed and are attributed to the 9 L polytype and to OH complexes.

Far infrared study of YBa2Cu3O6

Abstract We present far infrared reflectance spectra of YBa 2 Cu 3 O 6 and observe 15 and 20 oscillators respectively at 300 and 17 K. Our results are compared to other published optical phonon frequencies and to the infrared phonons of the superconductor YBa 2 Cu 3 O 7- x .

The infrared spectrum of Cd3As2

Abstract We present new measurements of infrared reflectivity of Cd 3 As 2 at 15 K. One plasmon and eleven phonon characteristics are determined by the fitting process that reveals weak dipolar moments in the structure.

Infrared reflectivity studies of quasi-two dimensional molybdenum oxides Mo4O11

Abstract Infrared reflectivity of the quasi-two dimensional oxides η-Mo4O11, has been investigated on single crystals, using polarized light, in the range of 300 – 4000 cm−1, at room temperature and in the charge density wave (CDW) state. At 300 K, the anisotropy of the reflectivity emphasizes the anisotropy of the conduction electron gas, with a metallic behavior within the (100) plane and a semiconducting behavior in the [100] direction. In this direction, the IR reflectivity is fitted with the phonon oscillators. At low temperature, the decrease of the IR reflectivity is consistent with the loss of carriers, induced by the CDW gap opening.

Infrared spectra of TiS3

Abstract Measurements are reported of the infrared reflectivity of the quasi-one-dimensional structure TiS3 with light polarizations both parallel and perpendicular to the chains. Most of the infrared-active phonons predicted by group theory are observed and compared with the Raman measurements.

Far-infrared study of Y2BaCuO5−x

Abstract Infrared reflectivity of the green phase Y 2 BaCuO 5− x has been measured at 300 and 15 K between 100 and 650 cm −1 . The spectra were fitted with phonon oscillators whose frequencies are compared to the Raman phonons. Some of the strong infrared phonons of YBa 2 Cu 3 O 7− x are also observed indicating the presence of the superconducting phase in Y 2 BaCuO 5− x material.

Infrared active phonons study in CsCoCl3

Abstract The infrared reflectance of the 1-D magnetic material CsCoCl3 is studied as a function of temperature. The five phonons predicted by group theory are detected and a phonon-magnetic excitation coupling is observed both in the breaking of the symmetry selection rules and in the evolution of the phonon parameters with temperature.

Infrared reflectance of YBa2(Cu1−xFex)3O7−u

Abstract This paper reports on the behavior of the infrared active phonon parameters of YBa 2 (Cu 1− x Fe x ) 3 O 7− u for x =0.05, 0.10 and 0.15 at 300 K and 15 K. The frequency shift of the 152 cm −1 , 191 cm −1 and 565 cm −1 modes correlate with the contraction of the c -axis. The frequency changes in the CuO 2 plane bending modes indicate that, for x =0.10 and 0.15, the Fe atoms substitute for Cu atoms on the Cu( 2 ) sites in addition to the Cu( 1 ) sites.