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Maiti S.K.,Saha Institute of Nuclear Physics | Maiti S.K.,Narasinha Dutt College
Solid State Communications | Year: 2010

The present work proposes an idea to remove the long standing controversy between the calculated and measured current amplitudes carried by a small conducting ring upon the application of an AharonovBohm (AB) flux φ. Within a mean field HartreeFock (HF) approximation we numerically calculate persistent current, Drude weight, low-field magnetic susceptibility and related issues. Our analysis may be inspiring for studying magnetic response in nano-scale loop geometries. © 2010 Elsevier B.V. All rights reserved.

Maiti S.K.,Saha Institute of Nuclear Physics | Maiti S.K.,Narasinha Dutt College
Physica Status Solidi (B) Basic Research | Year: 2011

The behavior of persistent current in a mesoscopic cylinder threaded by an Aharonov-Bohm flux φ{symbol} is carefully investigated within a Hartree-Fock mean field approach. We examine the combined effect of second-neighbor hopping integral and Hubbard correlation on the enhancement of persistent current in presence of disorder. A significant change in current amplitude is observed compared to the traditional nearest-neighbor hopping model and the current amplitude becomes quite comparable to experimental realizations. Our analysis is found to exhibit several interesting results which have so far remained unaddressed. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Maiti S.K.,Saha Institute of Nuclear Physics | Maiti S.K.,Narasinha Dutt College
Journal of Computational and Theoretical Nanoscience | Year: 2011

We explore the possibilities of current modulation at nano-scale level using mesoscopic rings. A single mesoscopic ring or an array of such rings is used for current modulation where each ring is threaded by a time varying magnetic flux φ which plays the central role in the modulation action. Within a tight-binding framework, all the calculations are done based on the Green's function formalism. We present numerical results for the two-terminal conductance and current which support the essential features of current modulation. The analysis may be helpful in fabricating mesoscopic or nano-scale electronic devices. Copyright © 2011 American Scientific Publishers.

Majhi B.R.,Sn Bose National Center For Basic Science | Samanta S.,Narasinha Dutt College
Annals of Physics | Year: 2010

Applying the Hamilton-Jacobi method we investigate the tunneling of photon across the event horizon of a static spherically symmetric black hole. The necessity of the gauge condition on the photon field, to derive the semiclassical Hawking temperature, is explicitly shown. Also, the tunneling of photon and gravitino beyond this semiclassical approximation are presented separately. Quantum corrections of the action for both cases are found to be proportional to the semiclassical contribution. Modifications to the Hawking temperature and Bekenstein-Hawking area law are thereby obtained. Using this corrected temperature and Hawking's periodicity argument, the modified metric for the Schwarzschild black hole is given. This corrected version of the metric, up to ℏ order is equivalent to the metric obtained by including one loop back reaction effect. Finally, the coefficient of the leading order correction of entropy is shown to be related to the trace anomaly. © 2010 Elsevier Inc.

Maiti S.K.,Narasinha Dutt College | Chakrabarti A.,Kalyani University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The Hubbard model on a Sierpinski gasket fractal is carefully examined within a Hartree-Fock mean-field approach. We examine the influence of a magnetic flux threading the gasket on its ground-state energy, persistent current and the Drude weight. Both an isotropic gasket and its anisotropic counterpart have been examined. The variance in the patterns of the calculated physical quantities are discussed for two situations, viz, at half filling and when the "band" is less than half filled. The phase reversal of the persistent currents and the change in the Drude weight as a function of the Hubbard interaction are found to exhibit interesting patterns that have so far remained unaddressed. © 2010 The American Physical Society.

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