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Mallik G, Kabiraj A, Swain DK, Dash PP, Kumari P, Rath S. Entropy-driven nonequilibrium phonon-stimulated electron-phonon coupling in tin dioxide nanorods. Phys Rev E 2024; 109:024213. [PMID: 38491670 DOI: 10.1103/physreve.109.024213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 01/15/2024] [Indexed: 03/18/2024]
Abstract
Nonequilibrium (NEQ) phonon fluctuation in a nanosystem has been studied through the statistical assessment of the entropy-production and -consumption events in ultrasmall tin dioxide (SnO_{2}) nanorods. Size- and shape-dependent alteration in free energy leading to modulation of the probability distribution function of the phonon dynamics has been observed from the x-ray diffraction and Raman scattering characterizations. The Gallavotti-Cohen nonequilibrium fluctuation theorem has been utilized to qualitatively describe the aforementioned behaviors under the influence of a global flux. The observation of entropy consumption and thermodynamically favorable entropy-production events indicates the presence of NEQ fluctuations in the phonon modes. The effective energy scale of fluctuation in driven phonon modes, dissipating energy faster than relaxation time, is quantified on the order of nanojoules. From optical absorption and photoluminescence studies, the observation of the electron-phonon coupled state confirms the interaction of the NEQ phonons with electrons. The strength of the coupling has been estimated from the temperature-independent Barry center shift and found to be enhanced to 5.35. Valence band x-ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy analyses reconcile NEQ phonon mediated alteration of the valence band density of states, activation of silent phonon modes, and superior excitonic transitions, suitable for the new generation of ultrafast quantum device applications.
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Affiliation(s)
- G Mallik
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni-752050, Khordha, Odisha, India
| | - A Kabiraj
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni-752050, Khordha, Odisha, India
| | - D K Swain
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni-752050, Khordha, Odisha, India
| | - P P Dash
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni-752050, Khordha, Odisha, India
| | - P Kumari
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni-752050, Khordha, Odisha, India
| | - S Rath
- School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni-752050, Khordha, Odisha, India
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Kabiraj A, Mallik G, Dash PP, Kumari P, Bandyopadhyay M, Rath S. Observation of non-equilibrium fluctuation in the shear-stress-driven hemoglobin aggregates. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:131. [PMID: 38123828 DOI: 10.1140/epje/s10189-023-00389-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023]
Abstract
Non-equilibrium fluctuations caused by the rearrangement of hemoglobin molecules into an aggregate state under shear stress have been investigated experimentally. The flow response under the shear stress (σ) corroborates the presence of contrasting aggregate and rejuvenation states governed by entropy production and consumption events. From the time-dependent shear rate fluctuation studies of aggregate states, the probability distribution function (PDF) of the rate of work done is observed to be spread from negative to positive values with a net positive mean. The PDFs follow the steady-state fluctuation theorem, even at a smaller timescale than that desired by the theorem. The behavior of the effective temperature (Teff) that emerges from a non-equilibrium fluctuation and interconnects with the structural restrictions of the aggregate state of our driven system is observed to be within the boundary of the thermodynamic uncertainty. The increase in Teff with the applied σ illustrates a phenomenal nonlinear power flux-dependent aggregating behavior in a classic bio-molecular-driven system.
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Affiliation(s)
- A Kabiraj
- Nanostructure and Soft Matter Physics Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni, Bhubaneswar, 752050, India
| | - G Mallik
- Nanostructure and Soft Matter Physics Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni, Bhubaneswar, 752050, India
| | - P P Dash
- Nanostructure and Soft Matter Physics Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni, Bhubaneswar, 752050, India
| | - P Kumari
- Nanostructure and Soft Matter Physics Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni, Bhubaneswar, 752050, India
| | - M Bandyopadhyay
- Statistical Mechanics Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni, Bhubaneswar, 752050, India
| | - S Rath
- Nanostructure and Soft Matter Physics Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Jatni, Bhubaneswar, 752050, India.
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Grimaldi G, Leo A, Nigro A, Pace S, Braccini V, Bellingeri E, Ferdeghini C. Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material. Sci Rep 2018; 8:4150. [PMID: 29515198 PMCID: PMC5841287 DOI: 10.1038/s41598-018-22417-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/19/2018] [Indexed: 11/09/2022] Open
Abstract
Anisotropy effects on flux pinning and flux flow are strongly effective in cuprate as well as iron-based superconductors due to their intrinsically layered crystallographic structure. However Fe(Se,Te) thin films grown on CaF2 substrate result less anisotropic with respect to all the other iron based superconductors. We present the first study on the angular dependence of the flux flow instability, which occurs in the flux flow regime as a current driven transition to the normal state at the instability point (I*, V*) in the current-voltage characteristics. The voltage jumps are systematically investigated as a function of the temperature, the external magnetic field, and the angle between the field and the Fe(Se,Te) film. The scaling procedure based on the anisotropic Ginzburg-Landau approach is successfully applied to the observed angular dependence of the critical voltage V*. Anyway, we find out that Fe(Se,Te) represents the case study of a layered material characterized by a weak anisotropy of its static superconducting properties, but with an increased anisotropy in its vortex dynamics due to the predominant perpendicular component of the external applied magnetic field. Indeed, I* shows less sensitivity to angle variations, thus being promising for high field applications.
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Affiliation(s)
| | - Antonio Leo
- CNR SPIN, Salerno, Fisciano, 84084, Italy
- Physics Department, University of Salerno, Fisciano, 84084, Italy
| | - Angela Nigro
- CNR SPIN, Salerno, Fisciano, 84084, Italy
- Physics Department, University of Salerno, Fisciano, 84084, Italy
| | - Sandro Pace
- CNR SPIN, Salerno, Fisciano, 84084, Italy
- Physics Department, University of Salerno, Fisciano, 84084, Italy
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