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Rabeet Singh
12109066
Study of adiabatic connection in density functional theory
29 December 2014 (Monday)
10.30 am
FB-382

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Arif Warsi Laskar
1220963
Manipulating states of photons with atoms
20 November 2014 (Thursday)
10.30 am
FB-382

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Rajan Singh
12209067
Optical detection of a weak scatterer
19 November 2014 (Wednesday)
11 am
FB-382

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Ankit Kumar
12209062
High Jc states in Iron Pnictides
7 November 2014 (Friday)
11 am
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Rajesh Kumar
12209068
Periodically patterned sculptured thin films for optical applications
20 October 2014 (Tuesday)
11 am
FB-382
Sculptured thin films (STFs) are three dimensional self-organized nanostructured materials that can be deposited to form well-defined structures by vapor deposition at large oblique angles. Periodically patterned STF (PP-STF) with spatially organized arrangements of the nano structures are made by deposition on pre-patterned substrates and show remarkable optical applications such as opticalactivity, surface enhanced spectroscopy, photonic crystal sensors etc. The large anisotropy and chirality in the optical response of STF make them potential candidates for incorporating in optical devices for control of polarization and directional emission/absorption. Large local field enhancements in metallic STF and the possibility of finely tuning their resonance through external means or fields makes them suitable candidates for surface enhance spectroscopic like surface enhance fluorescence (SEF) and surface enhance Raman scattering (SERS). In this seminar, I will begin by discussing the growth mechanisms of these PP-STF fabricated by glancing angle deposition technique and then describe some of the novel optical properties of these PP-STF. Finally, I will discuss about surface enhanced fluorescence and SERS from metallic sculptured thin films.

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Rameshwari Naorem
12209873
Scattering of electromagnetic radiation from disordered systems
14 October 2014 (Tuesday)
3 pm
FB-382
In multicomponent metallic alloys (like equimolar AlCuCoCrNi, MoCrFeNiCu & CuMnCoCrFeNi), configurational entropy may offset the tendency for compound formation to give rise to disordered solid solution(s). These alloys have been christened as high entropy alloys (HEA). The effect of the addition of multiple alloying elements to form a concentrated disordered solid solution on the x-ray diffraction (XRD) pattern is poorly understood. The role of atomic disorder and strain at the atomic level on the XRD pattern is also poorly characterized. Analogous to HEA with positional disorder one may envisage systems with orientational disorder, wherein the enhanced configurational entropy due to multiple orientational variants can stabilize a high symmetry phase, in spite of the strain in the lattice. In the case of the cluster compounds (of type AM4X8, where A is a trivalent atom like Ga, Ge or Al, M is a divalent transition metal and X is a chalcogenide), the strain arises due to Jahn-Teller distortion of tetrahedral clusters of transition metal ions. Further, compounds with both positional and orientational disorder can be envisaged. The effect of this combined disorder in cluster compounds on the XRD patterns and on structural, magnetic and transport properties are yet to be studied critically. Systems with orientational disorder of multiple origins (structural and spin) have not been studied in detail either from a stability perspective or from a scattering perspective.  On a larger length scale (optical wavelengths) chiral structures have been synthesized for many applications like antennas and arrays, antenna radome and waveguides. Scattering of coherent light waves from systems with chiral disorder offers interesting possibilities.

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Mohammad Zaffar
12109873
Mueller matrix Imaging in human tissue
29 August, 2014 (Friday)
10:30 am
FB-382