Electronic Properties and Magnetization of Mn-Doped Semiconductor Surface/Interface
Abstract
The understanding of Transition metal (Mn) impurity on semiconductingsurface have opened a wide scope of investigation based on the localstructure, hybridization effect, electronic properties and magneticordering occurring on the surface/interface of the system. The preparedsurface/ interface has been probed in-situ by X-ray photoemission (XPS),X-ray absorption (XAS) and the resonant photoemission (ResPES)spectroscopies along with the parameterized configuration integration (CI)models to calculate the Mn spectral weight in core-level and valence bandphotoemission. Presence of electron correlation has been evident by anintermediate state in the process of photoemission channel. Change of thelineshape due to the transition from an overall N – 1 electron final state(RRAS channel) to an N -2 electron final state (normal Auger channel) isevidenced by the analysis of the experimental data, which also allowed theratio to be tracked between charge delocalization and core-hole timescales as the photon energy is tuned across the Mn L3 edge [1].This can beused as an analysis technique for presence of electron correlation intransition metal based inorganic system. In addition to this, angleresolved photoemission spectroscopy (ARUPS),a powerful technique has beendone for experimental band mapping to detect the evolution of surfacestates below the Fermi energy or Mn derived state crossing the Fermi edgeof the Mn:Ge(111) sample [2]; as compared to the calculated band structureby Density functional theory using LDA[4]. In the second section adescription will be given on the cation diffusion and hybridizationeffects at the Mn-GaSe(0001) interface probed by soft X-ray electronspectroscopies[3]. In all the above systems, magnetic properties have beenrevealed as characterized by SQUID magnetometer.References1. Tracking the excitation dynamics in the Mn:Ge(111) metallic interface by resonant electron spectroscopy, L. Sangaletti, *S. Dash*, A. Verdini , L. Floreano, A. Goldoni, G. Drera, S. Pagliara, A. Morgante, J. Phys.: Condens. Matter 24 (2012) 2355022. Angle resolved UV Photoemission study on Mn:Ge (111) surface, *S. Dash*, L Sangaletti, L petaccia et. al. in preparation3. Cation diffusion and hybridization effects at the Mn-GaSe(0001) interface, *S. Dash*, G. Drera, E. Magnano, F. Bondino, P. Galinetto, M.C. Mozzati, V. Aguekian, and L. Sangaletti to be submitted4. First-principles characterization of ferromagnetic Mn5Ge3 for spintronic applications, S. Picozzi and A. Continenza, A. J. Freeman
In the last couple of decades a theory has been developed byVasiliev to consider interacting theories of fields with spin greater than2 which is known as higher-spin gravity. This theory has received a lot ofattention recently in the context of AdS-CFT correspondence. The theory invarious dimensions is conjectured to be dual to well known conformal fieldtheories in the boundary. In the light of this recent development, we willdiscuss the higher-spin analogue of topologically massive gravity in threedimensions, which we call topologically massive higher-spin gravity. Wewill start with a brief introduction and motivation to consider higher-spintheories. This will be followed by a brief introduction and overview ofcurrent results in higher-spin theories and topologically massive gravity.This will be followed by our work on topologically massive higher-spingravity. We will discuss various semi classical as well as quantum resultsof the theory considered by us.
Electrochemical synthesis of different metal-conducting polymer composites and their modifications by gamma and heavy ion radiations
Abstract
The present work reports the two step electrochemical synthesis of processfor the fabrication of different metal conducting polymer composites (viz.Au-polyaniline, Au-polypyrrole and Ag-polypyrrole). Initially, conductingpolymers such as polyaniline and polypyrrole were electrochemicallysynthesized on different substrate using a chronopotentiometery techniquewith optimized process parameters. The synthesized conducting polymerfilms act as working electrode for the decoration of submicron metalparticles on the surface of conducting polymer films through acyclicvoltammetry (CV) technique. Later, these composite films wereirradiated with gamma and under high vacuum (~5×10-6 Torr) at roomtemperature with different heavy ion beams radiations at various fluencesranging. The composites are characterized by scanning electron microscopy(SEM), micro-Raman and X-ray diffraction spectroscopic techniques beforeand after irradiation. Raman studies revealed that structure of the filmsbecame disordered after irradiation, which was also observed in SEMimages. Detailed Raman and XRD spectroscopic analysis had been presentedand SEM investigations showed that the craters were formed in the filmswith increase of ion fluence. The present investigations explore theapplicability of irradiated composite films for sensor applications.
