In-Plane Spectral Weight Shift of Charge Carriers in YBa2Cu3O6.9YBa_2Cu_3O_{6.9}

The temperature dependent redistribution of the spectral weight of the $CuO_2$ plane derived conduction band of the $YBa_2Cu_3O_{6.9}$ high temperature superconductor (T_c = 92.7 K) was studied with wide-band (from 0.01 to 5.6 eV) spectroscopic ellipsometry. A superconductivity - induced transfer of the spectral weight involving a high energy scale in excess of 1 eV was observed. Correspondingly, the charge carrier spectral weight was shown to decrease in the superconducting state. The ellipsometric data also provide detailed information about the evolution of the optical self-energy in the normal and superconducting states

Infrared studies of a La_(0.67)Ca_(0.33)MnO_3 single crystal: Optical magnetoconductivity in a half-metallic ferromagnet

The infrared reflectivity of a La_(0.67)Ca_(0.33)MnO_3 single crystal is studied over a broad range of temperatures (78–340 K), magnetic fields (0–16 T), and wave numbers (20–9000cm^(-1)). The optical conductivity gradually changes from a Drude-like behavior to a broad peak feature near 5000cm-1 in the ferromagnetic state below the Curie temperature T_C=307K. Various features of the optical conductivity bear striking resemblance to recent theoretical predictions based on the interplay between the double exchange interaction and the Jahn-Teller electron-phonon coupling. A large optical magnetoconductivity is observed near T_C

Clinical Case of Goldenhar Syndrome in Psychiatric Practice

A clinical case of a rare genetic oculo-auriculo-vertebral syndrome (Goldenhar syndrome) is presented in a young man of 18 years old, who was first sent for examination and treatment to the psychiatric ward. A retrospective analysis of anamnestic information indicates the emergence of psychopathological disorders in childhood in the form of a delay in psychoverbal development, emotional immaturity, and delays in the development of social behavior. Subsequently, persistent encephalasthenic and neurosis-like disorders were complicated by the addition of affective disorders of the depressive-dysphoric type and psychotic disorders. The lack of a timely integrated therapeutic approach with the addition of psychopharmacotherapy, psychotherapy and social therapy led to the formation of specific personality changes in organic etiology with significant disorders in the emotional sphere (lability of emotions, irritability, outbursts of anger, constant resentment and dissatisfaction with others), a decrease in the level of cognitive activity and a tendency to chronic course of neurosis-like and affective disorders. A statement of persistent pronounced violations of mental functions during follow-up observation caused severe restrictions in the main areas of life (communication, behavior control, education, work) and social maladaptation of the patient, which was the basis for referral to medical and social examination with the establishment of a disability group

Interface features and electronic structure of Bi2SiO5/β-Bi2O3 hetero-junction

Atomic and electronic structure of Bi2SiO5/β-Bi2O3 hetero-junction was described by means of density functional theory. The interface was found to be narrow-gap semiconductor with indirect band gap. The redistribution of states near the Fermi level in hybrid structure and the impact of spin-orbit coupling are discussed

Infrared Studies of a La_{0.67}Ca_{0.33}MnO_3 Single Crystal: Optical Magnetoconductivity in a Half-Metallic Ferromagnet

The infrared reflectivity of a $\rm La_{0.67}Ca_{0.33}MnO_3$ single crystal is studied over a broad range of temperatures (78-340 K), magnetic fields (0-16 T), and wavenumbers (20-9000 cm$^{-1}$). The optical conductivity gradually changes from a Drude-like behavior to a broad peak feature near 5000 cm$^{-1}$ in the ferromagnetic state below the Curie temperature $T_C=307 K$. Various features of the optical conductivity bear striking resemblance to recent theoretical predictions based on the interplay between the double exchange interaction and the Jahn-Teller electron-phonon coupling. A large optical magnetoconductivity is observed near $T_C$.Comment: 4 pages, 4 figures, Latex, PostScript; The 7th Joint MMM-Intermag Conference,San Francisco, January 6-9, 1998; The Int. Conf. on Strongly Correlated Electron Systems, Paris, July 15-18,199

Anomalous oxygen isotope effect on the in-plane FIR conductivity of detwinned YBa2Cu316,18^{16,18}O6.9_{6.9}

We observe an anomalous oxygen isotope effect on the a-axis component of the far-infrared electronic response of detwinned YBa2Cu3$^{16,18}$O$_{6.9}$. For $^{18}$O a pronounced low-energy electronic mode (LEM) appears around 240 cm$^{-1}$. This a-axis LEM exhibits a clear aging effect, after one year it is shifted to 190 cm$^{-1}$. For $^{16}$O we cannot resolve a corresponding a-axis LEM above 120 cm$^{-1}$. We interpret the LEM in terms of a collective electronic mode that is pinned by `isotopic defects', i.e. by the residual $^{16}$O in the matrix of $^{18}$O.Comment: 10 pages, 2 figure

Formation of metallic magnetic clusters in a Kondo-lattice metal: Evidence from an optical study

Magnetic materials are usually divided into two classes: those with localised magnetic moments, and those with itinerant charge carriers. We present a comprehensive experimental (spectroscopic ellipsomerty) and theoretical study to demonstrate that these two types of magnetism do not only coexist but complement each other in the Kondo-lattice metal, Tb2PdSi3. In this material the itinerant charge carriers interact with large localised magnetic moments of Tb(4f) states, forming complex magnetic lattices at low temperatures, which we associate with self-organisation of magnetic clusters. The formation of magnetic clusters results in low-energy optical spectral weight shifts, which correspond to opening of the pseudogap in the conduction band of the itinerant charge carriers and development of the low- and high-spin intersite electronic transitions. This phenomenon, driven by self-trapping of electrons by magnetic fluctuations, could be common in correlated metals, including besides Kondo-lattice metals, Fe-based and cuprate superconductors.Comment: 30 pages, 6 Figure