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Institute of Physics, Bhubaneswar

An Autonomous Research Institute of Department of Atomic Energy, Govt. of India

  Seminars in Institute of Physics

Seminars in the year: 2010


  • Space and Time-like Electromagnetic Pion and Koan form Factors in Light -cone pQCD

    07-01-2010 At 04:00:00 PM

    Speaker: Prof. Udit Raha, Department of Physics, Taiwan University, Taiwan

    Category: Seminar of General Interest

    Venue: Lecture Hall

    Abstract

    We analyze the electromagnetic pion and koan form factors by including sofr and higher-twist effects within the framework of resumed perturbative QCD (pQCD) for both the space and time-like regions. We focus on the transition from the perturbative to non-perturbative behavior in the phenomenological intermediate energy regime. Using a modified “kT” factorization scheme with transverse degrees of freedom, we evaluate the non-perturbative soft contributions as distinct from the hard contributions, ensuring no double counting via the vector Ward Identity at Q2=0. The soft contributions are obtained via local quark-hadron duality while the hard contributions rest on the well known factorization ansatz with intrinsic transverse momentum dependence of the distribution amplitudes modeled via the Brodsky-Huang-Lepage ansatz. Our analysis shows that while the perturbative twist-2 hard part prevails for large Q2 beyond 100-150 GeV2 or so, for low and moderate momentum transfers, say, below 10-16 GeV2, the soft contributions dominate in the space-like region and the twist-3 contributions dominate in the time-like region. Thus, we demonstrate the importance of including the genuine non-perturbative soft and power suppressed twist-3 contributions for simultaneously explaining the space and time-like experimental form factor data to a reasonable good accuracy.

  • Zinc oxide nanorods grown by the hydrothermal technique and their selective growth

    11-01-2010 At 12:00:11 AM

    Speaker: Prof. S. Nozaki, Dept. of Electronic Enginering University of Electrocommunication Tokyo, Japan

    Category: Seminar of General Interest

    Venue: Library Conference Hall

    Abstract

    Zinc oxide (ZnO) nanorods were grown on various substrates by the hydrothermal techique, and the effects of a substrate to be used on the growth of ZnO nanorods were studied. ZnO nanorods could grow vertically on a GaN but not on a Si substrate. However, they could grow on a Si substrate coated with a thick Ag film.The crystallinity and luminescence characteristic are also affected by a substrate to be used. It was also found that an array of ZnO nanorods could be formed by selective growth of ZnO on the e-beam lithographed resist pattern.

  • Double Beta decay simulation study of CdW04 detector

    19-01-2010 At 04:00:00 PM

    Speaker: Dr. Surja K. Ghorui, IIT, Kharagpur

    Category: Seminar of General Interest

    Venue: Library Lecture Hall

    Abstract

  • Surface Engineering of Polymers by RF plasma treatment for biomedical Applications

    20-01-2010 At 04:00:00 PM

    Speaker: Dr.Gomathi N, IIT, Kharagpur

    Category: Experimental Physics Group Seminar

    Venue: Library Lecture Hall

    Abstract

  • The dynamics of droplets bouncing on a liquid interface: a macroscopic type of wave-particle duality.

    20-01-2010 At 11:30:00 AM

    Speaker: Prof. Yves Couder (Univ. Paris 7, France)

    Category: Seminar of General Interest

    Venue: Library Lecture Hall

    Abstract

  • Synthesis and characterization of Si nanoclusters in Si using ion implantation

    25-01-2010 At 04:00:00 PM

    Speaker: Mrs. Gayatri Sahu, IOP

    Category: Synopsis Presentation Talk

    Venue: Library Lecture Hall

    Abstract

  • Synthesis of II - IV semiconductor nanomaterials by chemical precipitation and LECBD techniques and their characterization

    25-01-2010 At 12:00:11 AM

    Speaker: Amulya Krishna Mohapatra, IOP

    Category: Experimental Condensed Matter Group Seminar

    Venue: Library Lecture Hall

    Abstract

  • Ion beam sputtering induced nanostructured semiconductor surfaces

    05-02-2010 At 12:00:11 AM

    Speaker: Dr. Vinay Venugopal, PDF, IOP

    Category: Experimental Condensed Matter Group Seminar

    Venue: Lecture Hall

    Abstract

  • Solution in search of a problem

    08-02-2010 At 04:00:00 PM

    Speaker: Prof. A. Khare, IOP

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

  • Self Organized Surface morphology on silica induced by High energy Heavy Ions

    15-02-2010 At 04:00:00 PM

    Speaker: Dr. K. G. M. Nair , IGCAR, Kalpakkam

    Category: Seminar of General Interest

    Venue: Lecture Hall

    Abstract

  • A Search for TCO

    17-02-2010 At 04:00:00 PM

    Speaker: Suman Nandy Department of Physics, Jadavpur University, Kolkata

    Category: Condensed Matter Group Seminar

    Venue: IOP Lecture Hall

    Abstract

    Recently there is tremendous interest in transparent conducting oxides(TCOs) in general and p-type TCOs in particular. Development of p-typetransparent conducting oxides are essential for the oxide electronics andits applications. Although significant advancement has taken place overthe past few years in this field, still a long way is to go to use thesematerials in actual devices. In my research work, I have tried to developsome route for the synthesis of two prototype p-type TCO materials,namely, NiO and CuAlO2. Also one of the major aims is to understand andexplain some experimental findings such as band gap narrowing in NiO dueto heavy doping etc. The synthesized films were characterized by varioustechniques like XRD, SEM, HRTEM, XPS etc. In this presentation, I shallemphasize on the synthesis and characterizations of nickel oxide thin filmas a p-type material.

  • Formulation of Calculus on Fractal Curves in R^n and Physical Application

    24-02-2010 At 12:00:11 AM

    Speaker: Dr. Seema E. Satin (University of Pune)

    Category: TPSC Seminar

    Venue: Lecture Hall

    Abstract

    It is well known that fractals pervade nature. For example obsereved pathof a quantum mechanical particle or Brownian and Fractional Browniantrajectories are known to be fractals and are continuous butnon-differentiable. I will present a new calculus on fractal curves suchas the von-Koch curve. This will include a Riemann-like integral along afractal curve called the F^alpha-integral, where alpha denotes thedimension of the fractal curve. Also, a corresponding derivative, calledF^alpha-derivative will be introduced. I will discuss various aspects andresults of this Calculus. The second part of the talk will consist of theapplication of this Calculus to Fokker-Planck equation on Fractal Curves.I will start with a Chapmann-Kolmogorov equation on fractal curves andtalk about fractal diffusion and drift coefficients for a suitabletransition probability. In this process, a diffusion equation on fractalcurves will be obtained and finally I will show, how the probabilitydistribution shows deviation from ordinary diffusive behaviour due tounderlying fractal space.

  • Chirality, hawking effect and black hole spectroscopy

    25-02-2010 At 04:00:00 PM

    Speaker: Dr. Bibhas Ranjan Majhi, S.N. Bose Centre, Kolkata

    Category: High Energy Group Seminar

    Venue: Lecture Hall

    Abstract

  • Is the Universe Isotropic ?

    03-03-2010 At 04:00:00 PM

    Speaker: Prof. Pankaj, Jain,Physics Dept., IIT Kanpur

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

  • A Scale Invariant Standard Model

    04-03-2010 At 04:00:00 PM

    Speaker: Prof. Pankaj Jain , Physics Dept.,IIT Kanpur

    Category: TPSC HEP Seminar

    Venue: Lecture Hall

    Abstract

  • Conversion process in Neutron star

    05-03-2010 At 04:30:00 PM

    Speaker: Mr. Ritam Mallick, S.N.Bose Institute, Kolkata

    Category: TPSC Seminar

    Venue: Lecture Hall

    Abstract

  • Hints of Integrability Beyond Planer Limit

    11-03-2010 At 04:00:00 PM

    Speaker: Dr. Tanay K. Dey

    Category: High Energy Group Seminar

    Venue: Lecture Hall

    Abstract

  • From Worldsheet to Space - Time

    15-03-2010 At 04:00:00 PM

    Speaker: Prof. Partha Mukhopadhyay, Matscience, Chennai

    Category: High Energy Group Seminar

    Venue: Lecture Hall

    Abstract

  • Two photon Contribution to Elastic ep Scattering in a Non-local Field Formalism

    23-03-2010 At 04:00:00 PM

    Speaker: Subhadip Mitra, IMSc.

    Category: TPSC HEP Seminar

    Venue: Lecture Hall

    Abstract

  • Regulaltion by motor proteins in active vesicle transport and structural stability of Biofilaments

    31-03-2010 At 04:00:00 PM

    Speaker: Dr. Sudipto Muhuri, Universityof Saarbrucken, Germany

    Category: Condensed Matter Group Seminar

    Venue: Lecture Hall

    Abstract

  • Are there long lived massive string states?

    15-04-2010 At 04:00:00 PM

    Speaker: Prof. R. Ramachandran, IISER, Pune

    Category: High Energy Group Seminar

    Venue: Lecture Hall

    Abstract

  • A study on nucleation and growth mechanism through synthesis of II-VI semiconductor nanomaterials by chemical precipitation and LECBD technique

    16-04-2010 At 12:00:11 AM

    Speaker: Amulya Krishna Mohapatra, IOP

    Category: Synopsis Presentation Talk

    Venue: Lecture Hall

    Abstract

  • Recursive structures in string theory

    19-04-2010 At 04:00:00 PM

    Speaker: Dr. Anirban Basu, IOP

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

  • Polymer Friction by Stochastic Bond Rupture

    06-05-2010 At 12:00:00 PM

    Speaker: Dr. Pallavi Debnath, Max Planck Institute

    Category: Condensed Matter Group Seminar

    Venue: Lecture Hall

    Abstract

  • Causal quantum fields

    28-05-2010 At 04:00:00 PM

    Speaker: Prof. S. Mallik, S.I.N.P. Kolkata

    Category: HEP Seminar of General Interest

    Venue: Lecture Hall

    Abstract

    I shall follow the book by Weinberg, Quantum Theoryof Fields, Vol I, to construct the causal quantum fields. Butthere will be little in this talk that will appear new to you.In particular, the end result of this talk is known to you sinceyour M.Sc. days.

  • Asymptotic shape of an Eulerian Walker on a Square Lattice

    21-06-2010 At 12:00:00 PM

    Speaker: Rajeev Kapri, IISER, Mohali

    Category: CMP Seminar

    Venue: Lecture Hall

    Abstract

  • UNIFIED INVESTIGATION OF FUSION, RESONANCE AND SCATTERING IN HEAVY ION COLLISIONS

    23-06-2010 At 04:00:00 PM

    Speaker: Bidhubhusan Sahu, North Orissa University, Baripada

    Category: Seminar of General Interest

    Venue: Lecture Hall

    Abstract

    The number of potential that admit simple analytical expressions for the wave functions as well as the reflection and transmission amplitudes is limited. However, various physical problems in different disciplines of science need to be addressed by the interaction potentials which may not allow simple solution in the format of Schrödinger equation. In the general case, the Schrödinger equation is solved numerically or by approximating the studied potential by solvable ones. But the question arises whether it is possible to obtain simple and easy-to-use expressions for reflection and transmission coefficients for a smoothly varying potential which is not amenable to exact analytical solutions and evaluate the correct eigenvalues which represent bound, quasi-bound, and resonances states etc., generated by the potential. It may be mentioned that the applicability of the popular Runge-kutta method of numerical integration of Schrödinger equation is exposed in the cases of long ranged potentials having nonzero values at large distances, nevertheless, it is possible to obtain an exact solution by imposing constraints on the potentials. We derive the general expressions for reflection and transmission coefficients for a potential constituting n number of rectangular wells and barriers. These expressions are readily used for the estimation of eigenvalues of a smooth potential which is simulated by a multi-step potential. The applicability of this method is demonstrated in this work with success in potentials with different forms including the most versatile Ginocchio potential where the widely used numerical method like Runge-kutta integration algorithm fails to yield the result. Accurate evaluation of eigenvalues free from numerical problem for any form of potentials, whether analytically solvable or not, is the highlight of our multi-step approximation method in the theory of potential scattering. Here we give a brief review of heavy ion scattering and fusion. We see that it is quiet difficult to find a unique potential that can take care of both scattering and fusion processes simultaneously. For the description of elastic scattering and fusion cross section simultaneously, we use the Woods-Saxon form for the internuclear potential with a very small value for the diffuseness parameter ′a′ and the imaginary part used for absorption of flux is taken to be weak. Further, this potential is not made dependent on incident energy. To analyze the data of angular variations of elastic scattering cross sections an analytical recursive formula of the partial wave scattering matrix for the total effective complex potential of nucleus-nucleus collisions is derived. Further, another expression of cross sections for the absorption from arbitrary small intervals is derived. This leads to the explanation of the fusion cross section data at various center-of-mass energies Ec.m. by collecting the absorption contributions in the interior region of the effective potential. By virtue of the weakly absorbing character, nucleus-nucleus potential supports resonance states in different partial wave trajectories. Consequently, occurrence of these resonances is shown to be the physical origin of the observed oscillatory structure in the variation respect to energy of the quantity D(Ec.m.) = d2(Ec.m.σfus)/dEc.m.2, the second derivative of the product Ec.m.σfus with respect to Ec.m.. We investigate two well known systems namely 12C+208Pb and 16O+208Pb, and obtain simultaneous and very successful explanations of cross sections for elastic scattering, fusion, and the result of D(Ec.m.). These results obtained by using our convenient multi-step approximation method demonstrate the unified description of scattering and fusion for interacting heavy ion systems.

  • ENERGETIC ION BEAMS: A TOOL FOR NANOTECHNOLOGY

    28-06-2010 At 04:00:00 PM

    Speaker: Dr.O.P.Sinha, AMITY Institute of Nanotechnology, AMITY Univ., U.P.

    Category: Seminar of General Interest

    Venue: Lecture Hall

    Abstract

    Nano-research requires the ability to form and characterize nanostructures. The precision and accuracy required to produce structures in the nanometer scale and to characterize them demand commensurate tools. Although several techniques (e.g. wet and dry etching techniques, electron-beam lithography, etc.) have been employed for the fabrication of nanostructures, ion irradiation has also been demonstrated to be promising tool for the fabrication of uniform and highly ordered quantum dot arrays. Ion irradiation is a promising tool for nanopatterning of materials’ surfaces because of its compatibility and reproducibility with easily controllable growth conditions. It has very high spatial selectivity and is not governed by chemical compatibility. Thus, one can tune physical properties of a material by varying the ion species and energy, the charge state, and the ion fluence. The present talk will deal with wide range of ion energy, starting from keV ions (at IOP, Krakow, Poland) to a few MeV ions (at IOP, Bhubaneswar) to hundreds of MeV ions (at IUAC, New Delhi) to demonstrate irradiation-induced nanoscale patterning of semiconductors (Ge, Si, GaAs, InP, GaSb, InSb, InAs) and alkali halide system (KBr).

  • Alpha-decay in S-matrix Approach

    07-07-2010 At 04:00:00 PM

    Speaker: Prof. C.S. Sastry, Deptt. of Physics, Ambrita School of Engineering, Coimbatore

    Category: Seminar of General Interest

    Venue: Lecture Hall

    Abstract

  • Possibility of a Type II DNA : negative interface energy

    09-07-2010 At 12:00:15 AM

    Speaker: Poulomi Sadhukhan

    Category: Condensed Matter Group Seminar

    Venue: Lecture Hall

    Abstract

  • Kitaev Model and Dimer Coverings

    14-07-2010 At 12:00:15 AM

    Speaker: Sumedha, NISER

    Category: Condensed Matter Group Seminar

    Venue: Lecture Hall

    Abstract

    In this talk I will review some recent articles in Kitaev model. Kitaev model was introduced by Alexei Kitaev in 2008. It is a quantum spin model with anisotropic couplings, which can be solved exactly in two dimensions.

  • Simple Analysis of IR Singularities at One-loop

    21-07-2010 At 04:00:00 PM

    Speaker: Ambresh Shivaji

    Category: High Energy Group Seminar

    Venue: Library Lecture Hall

    Abstract

  • Collective response of conduction electrons to photoelectron emission from rare gas nano-bubbles in aluminum

    02-08-2010 At 04:00:00 PM

    Speaker: Sudipta Roy Barman, IUC-DAE, Indore)

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

    Rare gas bubble in aluminum is an interesting embedded nanosystem, where the bubble radii have been reported to vary from fraction of a nm to less than 10 nm. Depending on implantation conditions. The repulsive pseudopotential of the rare gas atoms in A1 makes bubble formation energetically favourable. Because of their small size and proximity to the A1 surface, these bubbles exhibit quantum confinement and interference. In our laboratory, we have studied consequences of photoelectron emission from the rare gas bubbles using x-ray photoelectron spectroscopy. As a consequence of the nanometer size, the photo-hole formed by Xe 3d or Ar 2p photoemission is screened by the A1 conduction electrons, which substantially lowers their binding energy compared to the gas phase [1,2]. As the bubble size increases, the A1 conduction electron screening decreases and the binding energy increases. Ne 1s spectra unexpectedly exhibits two beaks, that we ascribe to the existence of a bimodal depth and size distribution of Ne bubbles [3]. Another interesting observation is existence of aluminum bulk and surface plasmon collective excitations in the core-level spectra of the rare gas bubbles, whose intensities are even higher than those of A1 metal [4]. Both intrinsic and extrinsic bulk plasmons are detected, but they exhibit diametrically opposite intensity variation due to change in the size and implantation depth. The intrinsic plasmon in 1ώp is observed because of their nano-meter size, and its intensity decreases with increasing size as the A1 conduction electron screening becomes weaker. On the other hand, the extrinsic plasmon contribution increases with implantation depth. Furthermore, evidence of bubble surface plasmon is obtained.References[1] C.Biswas, A.K. Shukla, S. Banik, S.R. Barman and A.Chakrabarti, Phys. Rev. Lett. 92, 115506 (2004)[2] R.S. Dhaka, C.Biswas, A.K. Shukla, S.R. Barman and A.Chakrabarti, Phys. Rev. B77, 104119 (2008).[3] R.S. Dhaka and S.R. Barman, Phys. Rev. B79, 125409 (2009)[4] R.S. Dhaka and S.R. Barman, Phys. Rev. Lett. 104, 036803 (2010)

  • Introduction to Inverse Photoemission : A Study of Unoccupied States.

    03-08-2010 At 04:30:00 PM

    Speaker: Prof. S. R. BARMAN, IUC-DAE, Indore

    Category: General Seminar

    Venue: Lecture Hall

    Abstract

  • 10+1 to 3+1 in an early universe with mutuallly BPS intersecting

    06-08-2010 At 03:00:00 PM

    Speaker: Samrat Bhowmick, IMSc.

    Category: HEP Seminar

    Venue: Lecture Hall

    Abstract

  • Spacetime and Noncommutative Geometry

    09-08-2010 At 04:00:00 PM

    Speaker: Prof. A.P. Balachandran, Physics Dept., Syracuse University, USA

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

    Attempts to make observations at Planck scales are likely to cause formation of black holes .They will limit the possibility of observation at these scales.Such limitations can be accounted for by making the coordinates of spacetime not commute, just as in quantum theory, the Heisenberg uncertainty principle is taken care of by noncommuting position and momentum. These ideas go back to the 1930's and Heisenberg and Schrodinger. This interesting history is traced. We then explain the formulation of such quantum spacetimes and their physical consequences. They modify the Pauli principle and lead to Pauli-forbidden transitions.They also lead to violations of causality at Planck scales with observable consequences for cosmic microwave background, Lorentz invariance, equality of particle-antiparticle lifetimes, CPT theorem etc. All these are reviewed in an elementary manner.

  • Effective Action at Finite Temperature

    11-08-2010 At 03:00:00 PM

    Speaker: Professor Ashok Das (Rochester University)

    Category: General Seminar

    Venue: Lecture Hall

    Abstract

  • Effect of Resonant Neutrino Oscillation on TeV Neutrino Flavor Ratio from Choked GRBs

    30-08-2010 At 04:00:00 PM

    Speaker: Prof. Sarira Sahu,Institute of Nuclear Science (ICN) National Autonomous University of Mexico (UN

    Category: Nuclear Physics - Seminar for General Interest

    Venue: Library Lecture Hall

    Abstract

    In the collapsar scenario of the long duration Gamma-Ray Bursts(GRBs), multi-TeV neutrino emission is predicted as the jet makes its waythrough the stellar envelope. Such a neutrino signalis also expected for more general ``failed'' GRBs in which aputative jet is ``choked'' by a heavy envelope.If the neutrino oscillation parameters are in the atmospheric neutrinooscillation range, we show that the resonant oscillation ofelectron neutrino to muon/ natu neutrino can take place within the innerhigh density region of the choked jet progenitor with a heavy envelope,altering the neutrino flavor ratio on itssurface to $Phi^s_{u_e}:Phi^s_{u_mu}:Phi^s_{u_ au}=5:11:2$.Considering vacuum oscillation of these neutrinos on their way toEarth, the final flavor ratio detected on Earth is further modifiedto either :1.095:1.095$ for thelarge mixing angle solution to the solar neutrino data, or 1:1.3:1.3 formaximal mixing among the muon and tau neutrinos in vacuum.

  • Sheared Soft Matter : Order, Chaos & Fluctuation

    03-09-2010 At 10:00:00 AM

    Speaker: Prof. A.K.Sood, IISc., Bangalore

    Category: Colloquium

    Venue: IOP Auditorium

    Abstract

  • Logarithemic corrections to extremal black hole

    07-09-2010 At 04:00:00 PM

    Speaker: Dr. Shamik Banerjee, HRI, Allahabad

    Category: HEP Seminar

    Venue: Lecture Hall

    Abstract

  • Markov chain model for the Indus script

    27-09-2010 At 04:00:00 PM

    Speaker: Ronojoy Adhikari, IMSC, Chennai

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

    The Indus script is one of the major undeciphered scripts ofthe ancient world. I will discuss the difficulties associated withdeciphering this script and present a theoretical framework, based onMarkov chains, within which the syntax of the script can be exploredsystematically. I will present key results from the Markov chain analysiswhich provide evidence in favour the hypothesis that the script was usedto represent natural language. The use of other probabilistic methods foranalysis corpora of linear sequences will also be briefly outlined.

  • Active Polar Filaments: Dynamics, Phase Transitions and Applications in Cell Biology

    27-09-2010 At 11:30:00 AM

    Speaker: Dr. Kripa Gowrishankar, Raman Research Institute, Bangalore

    Category: CMP Seminar

    Venue: Lecture Hall

    Abstract

    Coarse grained hydrodynamic theories have so far been successful indescribing patterns formed in in vitro mixtures of active polar filaments(eg Actin, Microtubules) and motors (Myosin, Dyenin, Kinesin). Thereexists little evidence of their validity in vivo.In this talk I will present a theoretical stdy of the dynamics of activepolar filaments on a two dimensional substrate. We determine that thesteady states of the equations of motion of these filaments aregenerically composed of inward pointing asters in different arrangements.The asters display an interesting dynamics in the presence of noise- theybreak up and reform with characteristic residence times, whosedistribution depends on the noise strength.I will further present evidence that the results are applicable to thepatterning of molecules on the cell surface. The evidence is based onanisotropy experiments of GPI-anchored proteins, a class of proteins thatassociate with Actin.

  • Structural modifications in solids induced by swift heavy ions

    13-10-2010 At 04:00:00 PM

    Speaker: Dr. A. Benyagoub,CIMAP (ex-CIRIL-GANIL), CEA-CNRS-ENSICAEN-Université de Caen, Bd Henri Becquerel,

    Category: General Seminar

    Venue: Lecture Hall

    Abstract

    The intense electronic excitations and ionizations released in the wake ofswift heavy ions can induce important structural modifications in solids.It is well known that the irradiation of many crystalline materials withswift heavy ions generally leads to structural disorder which spans frompoint defect creation up to total amorphization. However, there is nowgrowing evidence that the structural changes induced by the irradiationwith swift heavy ions are not limited to damage creation but can alsocomprise crystalline-to-crystalline phase transitions. More recently,these effects were also enriched by the finding that swift heavy ions caninduce epitaxial recrystallization of predamaged layers produced bynuclear collisions.From the fundamental point of view, two types of models, either based onthe ‘Coulomb explosion’ concept or the ‘thermal spike’ mechanism areusually proposed to account for swift heavy ion induced atomic movements.Since for both models the timescales of the involved processes are quiteinaccessible to usual characterization techniques, it is very difficult toidentify the actual mechanism. Nevertheless, the recent study ofirradiation effects in the twin oxides zirconia and hafnia, which sharemany physical and chemical properties, offered the unique opportunity toimpose drastic constraints on the models. This comparative study allowedto demonstrate that the thermal spike is the appropriate mechanism whichgoverns the transition from the monoclinic to the tetragonal phase inzirconia and hafnia rather than the Coulomb explosion process.In this contribution, these different types of swift heavy ion inducedphase transitions in solids (i.e., crystalline-to-amorphous,crystalline-to-crystalline and amorphous-to-crystalline transformations)will be illustrated with recent experiments performed at the GANILaccelerator and the mechanisms leading to these effects will be discussedand interpreted within a single view based on the thermal spike process.

  • Pd/TiOx/Ti-Au (x<2) Metal-Active Insulator-Metal (MIM) hydrogen gas sensor at elevated temperatures

    20-10-2010 At 04:00:00 PM

    Speaker: Dr. Surajit Hazra, Univ. of Brescia, Italy

    Category: General Seminar

    Venue: Lecture Hall

    Abstract

    Detection of flammable and toxic gases is a subject of growing importancein both domestic and industrial environments. Different deviceconfigurations based on metal oxides have been used so far. MIM is onesuch important configuration to achieve high sensitivity and fastresponse.Polycrystalline titanium dioxide was grown by thermal oxidation at 800oCon 0.25 mm thick titanium substrates with gold coating on the backsurface. Resistivity, carrier density & mobility were measured at roomtemperature. The grown oxide showed n-type conducitivity. Pd metal dots(1.5 mm dia) were deposited on the oxide surface, using e-beam evaporationtechnique, to fabricate Pd/TiOx/Ti-Au (x<2) MIM sensor structure. The I-Vstudy was carried out with 500 ppm hydrogen in the temperature range 200 -350oC and the current increased upon exposure to hydrogen. The sensitivityand the change in barrier height were calculated and were found tomaximize at 300oC beyond which the values started decreasing. The responsetime as calculated from the transient response characteristics was 16 secat 300oC.In this talk, the thin film preparation technique and associatedcharacterizations along with the sensor response will be discussed indetail.

  • Emergence of exotic phenomena in superconductor/ferromagnet heterostructures

    02-11-2010 At 04:00:00 PM

    Speaker: Dr. Debakanta Samal, Indian Institute of Science, Bangalore.

    Category: CMP Seminar

    Venue: Lecture Hall

    Abstract

    The study of the co-existence of singlet superconductivity and ferromagnetism is one of the most fascinating and challenging areas of resaerch since both the phenomenon are quantum mechanically antagonistic to each other. However, the coexistence can easily be achieved in artificially fabricated superconductor–ferromagnet heterostructures and these systems offer unique opportunities to study the interplay beteween two competing order parameters and to conceive novel quantum states. Our investigations on different superconducting(S)/ferromagnetic(F) heterostructures fabricated by pulsed laser deposition reveal an intense suppression of superconductivity due to the magnetic proximity effect and the injection of spin polarised quasiparticles from the F electrode. The current dependent transport studies exhibit a significant reduction of the superconducting Tc in the S/F bilayers as compared to single S layer and strictly adhers to I2/3 de-pairing effect. Astonishingly, the superconducting Tc in YBa2Cu3O7-/ La0.5Sr0.5CoO3 bilayers is observed to be much lower as compared to YBa2Cu3O7-/La0.7Sr0.3MnO3 ones. This points to the fact that in addition to the spin polarisation of the ferromagnetic electrode, other factors such as (a) interfce transparency (b) magnetic domain state and (c) the stray field associated with the F layer might play important role in tuning the S order parameter. Magnetotransport studies reveal a remarakable reduction of activation energy (U) and a logarithmic dependence of “U” on the applied magnetic field in S/F heterostructures. This signifies the signature of the existence of decoupled 2D pancake vortices that can arise from the weakening of the S coherence length () due to the presence of F layers and the dominance of intralayer vortex-vortex interaction over the interlayer one.References:1. A.I. Buzdin, Rev. Mod. Phys. 77, 935-976 (2005).2. D. Samal, C. Shivakumara and P.S. Anil Kumar, Phys. Rev.B 77, 094510 (2008)3. D. Samal, and P.S. Anil Kumar, J. Phys.: Condens. Matter. 21, 492203 (2009) (IOP Select)4. D. Samal, Chanchal Sow and P.S. Anil Kumar, J. Phys.:Condens. Matter. 22, 295701(2010)5. D. Samal and P. S. Anil Kumar (J. Supercond. Nov. Magn. in press)Delete & Prev | Delete & NextMove to:

  • The Dirac equation in condensed matter

    08-11-2010 At 04:00:00 PM

    Speaker: R. Shankar (IMSc, Chennai)

    Category: Colloquium

    Venue: Lecture Hall

    Abstract

  • Kitaev Model and its generalization

    09-11-2010 At 04:00:00 PM

    Speaker: Prof. R.Shankar, IIMSc., Chennai

    Category: Informal Seminar

    Venue: Lecture Hall

    Abstract

  • Thermodynamic Geometry and Phase Transition in AdS Black Holes

    10-11-2010 At 04:00:00 PM

    Speaker: Dr. A. Sahay, IIT, Kanpur

    Category: HEP Seminar

    Venue: Lecture Hall

    Abstract