14 results on '"Kazi Rafsanjani Amin"'
Search Results
2. Multifractal Conductance Fluctuations in High-Mobility Graphene in the Integer Quantum Hall Regime
- Author
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Kazi Rafsanjani Amin, Ramya Nagarajan, Rahul Pandit, and Aveek Bid
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Condensed Matter - Mesoscale and Nanoscale Physics ,Statistical Mechanics (cond-mat.stat-mech) ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,FOS: Physical sciences ,General Physics and Astronomy ,Condensed Matter - Statistical Mechanics - Abstract
We present the first experimental evidence for the multifractality of a transport property at a topological phase transition. In particular, we show that conductance fluctuations display multifractality at the integer-quantum-Hall $\nu=1 \longleftrightarrow \nu=2$ plateau-to-plateau transition in a high-mobility mesoscopic graphene device. We establish that to observe this multifractality, it is crucial to work with very high-mobility devices with a well-defined critical point. This multifractality gets rapidly suppressed as the chemical potential moves away from these critical points. Our combination of multifractal analysis with state-of-the-art transport measurements at a topological phase transition provides a novel method for probing such phase transitions in mesoscopic devices., Comment: 10 pages, 4 figures
- Published
- 2022
3. Loss mechanisms in TiN high impedance superconducting microwave circuits
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Kazi Rafsanjani Amin, Carine Ladner, Guillaume Jourdan, Sébastien Hentz, Nicolas Roch, Julien Renard, Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Circuits électroniques quantiques Alpes (NEEL - QuantECA), and ANR-19-CE47-0007,GRAPHMON,Circuits quantiques supraconducteurs à base de graphène(2019)
- Subjects
Physics and Astronomy (miscellaneous) ,[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph] ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] - Abstract
Aluminum-based platforms have allowed to reach major milestones for superconducting quantum circuits. For the next generation of devices, materials that are able to maintain low microwave losses while providing new functionalities, such as large kinetic inductance or compatibility with CMOS platform, are needed. Here, we report on a combined direct current and microwave investigation of titanium nitride films of different thicknesses grown using CMOS compatible methods. For microwave resonators made of 3 nm thick TiN, we measured large kinetic inductance [Formula: see text] pH/sq, high mode impedance of [Formula: see text] kΩ while maintaining microwave quality factor [Formula: see text] in the single photon limit. We present an in-depth study of the microwave loss mechanisms in these devices that indicates the importance of quasiparticles and provide insight for further improvement.
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- 2022
4. A gate-tunable graphene Josephson parametric amplifier
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Guilliam Butseraen, Arpit Ranadive, Nicolas Aparicio, Kazi Rafsanjani Amin, Abhishek Juyal, Martina Esposito, Kenji Watanabe, Takashi Taniguchi, Nicolas Roch, François Lefloch, Julien Renard, Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Circuits électroniques quantiques Alpes (NEEL - QuantECA), National Institute for Materials Science (NIMS), Laboratoire de Transport Electronique Quantique et Supraconductivité (LaTEQS), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), and ANR-19-CE47-0007,GRAPHMON,Circuits quantiques supraconducteurs à base de graphène(2019)
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electron ,noise ,Biomedical Engineering ,FOS: Physical sciences ,Bioengineering ,parametric ,microwaves ,low ,quantum ,dimension ,[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph] ,gas ,gate ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,General Materials Science ,Electrical and Electronic Engineering ,quantum sensing ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,computer ,Quantum Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,superconductivity ,carbon ,graphene ,dissipation ,semiconductor ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,optics ,amplifier ,technology ,readout ,nonlinear ,quantum circuit ,Quantum Physics (quant-ph) ,performance - Abstract
International audience; With a large portfolio of elemental quantum components, superconducting quantum circuits have contributed to dramatic advances in microwave quantum optics. Of these elements, quantum-limited parametric amplifiers have proven to be essential for low noise readout of quantum systems whose energy range is intrinsically low (tens of $\mu$eV ). They are also used to generate non classical states of light that can be a resource for quantum enhanced detection. Superconducting parametric amplifiers, like quantum bits, typically utilize a Josephson junction as a source of magnetically tunable and dissipation-free nonlinearity. In recent years, efforts have been made to introduce semiconductor weak links as electrically tunable nonlinear elements, with demonstrations of microwave resonators and quantum bits using semiconductor nanowires, a two dimensional electron gas, carbon nanotubes and graphene. However, given the challenge of balancing nonlinearity, dissipation, participation, and energy scale, parametric amplifiers have not yet been implemented with a semiconductor weak link. Here we demonstrate a parametric amplifier leveraging a graphene Josephson junction and show that its working frequency is widely tunable with a gate voltage. We report gain exceeding 20 dB and noise performance close to the standard quantum limit. Our results complete the toolset for electrically tunable superconducting quantum circuits and offer new opportunities for the development of quantum technologies such as quantum computing, quantum sensing and fundamental science.
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- 2022
5. Effect of dimensionality on the vortex-dynamics in type-II superconductor
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Kazi Rafsanjani Amin, John Jesudasan, Hemanta Kumar Kundu, Subroto Mukerjee, Pratap Raychaudhuri, and Aveek Bid
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Superconductivity ,Physics ,Phase transition ,Condensed matter physics ,Plane (geometry) ,Condensed Matter - Superconductivity ,FOS: Physical sciences ,02 engineering and technology ,Vorticity ,021001 nanoscience & nanotechnology ,01 natural sciences ,Vortex ,Superconductivity (cond-mat.supr-con) ,Phase (matter) ,Condensed Matter::Superconductivity ,0103 physical sciences ,010306 general physics ,0210 nano-technology ,Order of magnitude ,Phase diagram - Abstract
We explore the effects of sample dimensionality on vortex pinning in a type-II, low-$T_C$, s-wave superconductor, NbN, in the presence of a perpendicular magnetic field, $H$. We find significant differences in the phase diagrams in the magnetic field--temperature plane between 3-dimensional (3D) and 2-dimensional (2D) NbN films. The differences are most striking close to the normal-superconductor phase transition. We establish that these variances have their origin in the differing pinning properties in two different dimensions. We obtain the pinning strength quantitatively in both the dimensions from two independent transport measurements performed in two different regimes of vortex-motion -- (i) thermally assisted flux-flow (TAFF) regime and (ii) flux flow (FF) regime. Both the measurements consistently show that both the pinning potential and the zero-field free-energy barrier to depinning in the 3D superconductor are at least an order of magnitude stronger than that in the 2D superconductor. Further, we probed the dynamics of pinning in both 2D and 3D superconductor through voltage fluctuation spectroscopy. We find that the mechanism of vortex pinning-depinning is qualitatively similar for the 3D and 2D superconductors. The voltage-fluctuations arising from vortex-motion are found to be correlated only in the 2D superconductor. We establish this to be due to the presence of long-range phase fluctuations near the Berezinskii-Kosterlitz-Thouless (BKT) type superconducting transition in 2-dimensional superconductors.
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- 2020
6. Manipulation of Optoelectronic Properties and Band Structure Engineering of Ultrathin Te Nanowires by Chemical Adsorption
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Kazi Rafsanjani Amin, N. Ravishankar, Sangram Biswas, Abhishek K. Singh, Ahin Roy, Shalini Tripathi, and Aveek Bid
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Quenching ,Materials science ,business.industry ,Ab initio ,Nanowire ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,symbols.namesake ,Adsorption ,chemistry ,Electrical resistivity and conductivity ,symbols ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Tellurium ,Raman spectroscopy ,Electronic band structure - Abstract
Band structure engineering is a powerful technique both for the design of new semiconductor materials and for imparting new functionalities to existing ones. In this article, we present a novel and versatile technique to achieve this by surface adsorption on low dimensional systems. As a specific example, we demonstrate, through detailed experiments and ab initio simulations, the controlled modification of band structure in ultrathin Te nanowires due to NO2 adsorption. Measurements of the temperature dependence of resistivity of single ultrathin Te nanowire field-effect transistor (FET) devices exposed to increasing amounts of NO2 reveal a gradual transition from a semiconducting to a metallic state. Gradual quenching of vibrational Raman modes of Te with increasing concentration of NO2 supports the appearance of a metallic state in NO2 adsorbed Te. Ab initio simulations attribute these observations to the appearance of midgap states in NO2 adsorbed Te nanowires. Our results provide fundamental insights i...
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- 2017
7. Exotic Multifractal Conductance Fluctuations in Graphene
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Rahul Pandit, Aveek Bid, Kazi Rafsanjani Amin, Nairita Pal, and Samriddhi Sankar Ray
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Work (thermodynamics) ,General Physics and Astronomy ,FOS: Physical sciences ,lcsh:Astrophysics ,02 engineering and technology ,Physics::Data Analysis ,Statistics and Probability ,01 natural sciences ,Condensed Matter::Disordered Systems and Neural Networks ,law.invention ,law ,lcsh:QB460-466 ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,010306 general physics ,Scaling ,Quantum ,Universal conductance fluctuations ,Physics ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Graphene ,Conductance ,Multifractal system ,Eigenfunction ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,0210 nano-technology ,lcsh:Physics - Abstract
In quantum systems, signatures of multifractality are rare. They have been found only in the multiscaling of eigenfunctions at critical points. Here we demonstrate multifractality in the magnetic field-induced universal conductance fluctuations of the conductance in a quantum condensed matter system, namely, high-mobility single-layer graphene field-effect transistors. This multifractality decreases as the temperature increases or as doping moves the system away from the Dirac point. Our measurements and analysis present evidence for an incipient Anderson-localization near the Dirac point as the most plausible cause for this multifractality. Our experiments suggest that multifractality in the scaling behavior of local eigenfunctions are reflected in macroscopic transport coefficients. We conjecture that an incipient Anderson-localization transition may be the origin of this multifractality. It is possible that multifractality is ubiquitous in transport properties of low-dimensional systems. Indeed, our work suggests that we should look for multifractality in transport in other low-dimensional quantum condensed-matter systems. Multifractality is ubiquitous in classical systems but rare in quantum ones. Here the authors present observations demonstrating that universal conductance fluctuations in high-mobility single-layer graphene field-effect transistors are multifractal and may arise from Anderson-localization.
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- 2018
- Full Text
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8. Crumpled sheets of reduced graphene oxide as a highly sensitive, robust and versatile strain/pressure sensor
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Subhajit Kundu, Rammohan Sriramdas, Aveek Bid, N. Ravishankar, Kazi Rafsanjani Amin, and Rudra Pratap
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Materials science ,Graphene ,Oxide ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Pressure sensor ,0104 chemical sciences ,Highly sensitive ,law.invention ,chemistry.chemical_compound ,chemistry ,Interfacing ,Gauge factor ,Robustness (computer science) ,law ,General Materials Science ,Sensitivity (control systems) ,0210 nano-technology - Abstract
Sensing of mechanical stimuli forms an important communication pathway between humans/environment and machines. The progress in such sensing technology has possible impacts on the functioning of automated systems, human machine interfacing, health-care monitoring, prosthetics and safety systems. The challenges in this field range from attaining high sensitivity to extreme robustness. In this article, sensing of complex mechanical stimuli with a patch of taped crumpled reduced graphene oxide (rGO) has been reported which can typically be assembled under household conditions. The ability of this sensor to detect a wide variety of pressures and strains in conventional day-to-day applications has been demonstrated. An extremely high gauge factor (similar to 10(3)) at ultralow strains (similar to 10(-4)) with fast response times (
- Published
- 2017
9. Effect of ambient on electrical transport properties of ultra-thin Au nanowires
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Aveek Bid, Kazi Rafsanjani Amin, Abhishek K. Singh, Ahin Roy, N. Ravishankar, Sangram Biswas, and Subhajit Kundu
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Materials science ,Local density of states ,Physics and Astronomy (miscellaneous) ,Materials Research Centre ,Physics ,Nanowire ,Ab initio ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Adsorption ,chemistry ,Electrical transport ,Chemical physics ,Molecule ,Methanol ,0210 nano-technology ,Spectroscopy - Abstract
In this letter we present systematic studies of the dynamics of surface adsorption of various chemicals on ultra-thin single crystalline gold nanowires (AuNW) through sensitive resistance fluctuation spectroscopy measurements coupled with ab initio simulations. We show that, contrary to expectations, the adsorption of common chemicals like methanol and acetone has a profound impact on the electrical transport properties of the AuNW. Our measurements and subsequent calculations establish conclusively that in AuNW, semiconductor-like sensitivity to the ambient arises because of changes induced in its local density of states by the surface adsorbed molecules. The extreme sensitivity of the resistance fluctuations of the AuNW to ambient suggests their possible use as solid-state sensors. Published by AIP Publishing.
- Published
- 2016
10. Robust local and nonlocal transport in the topological Kondo insulator SmB6 in the presence of a high magnetic field
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Ramya Nagarajan, Aveek Bid, Sangram Biswas, Kazi Rafsanjani Amin, Sumanta Tewari, M. Ciomaga Hatnean, Suman Sarkar, and Geetha Balakrishnan
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Physics ,Spin states ,Magnetoresistance ,Condensed matter physics ,Scattering ,TK ,Kondo insulator ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Magnetic field ,Topological insulator ,Condensed Matter::Strongly Correlated Electrons ,Strongly correlated material ,QC ,Surface states - Abstract
SmB6 has been predicted to be a Kondo topological insulator with topologically protected conducting surface states. We have studied quantitatively the electrical transport through surface states in high-quality single crystals of SmB6. We observe a large nonlocal surface signal at temperatures lower than the bulk Kondo gap scale. Measurements and finite-element simulations allow us to distinguish unambiguously between the contributions from different transport channels. In contrast to general expectations, the electrical transport properties of the surface channels were found to be insensitive to high magnetic fields. We propose possible scenarios that might explain this unexpected finding. Local and nonlocal magnetoresistance measurements allowed us to identify possible signatures of helical spin states and strong interband scattering at the surface.
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- 2015
11. Effect of ambient on the resistance fluctuations of graphene
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Kazi Rafsanjani Amin and Aveek Bid
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Materials science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Physics and Astronomy (miscellaneous) ,Graphene ,business.industry ,Physics ,Spectral density ,FOS: Physical sciences ,Low frequency ,Noise (electronics) ,law.invention ,Chemical species ,law ,Electrical resistivity and conductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Optoelectronics ,Molecule ,Field-effect transistor ,business - Abstract
In this letter, we present the results of systematic experimental investigations of the effect of different chemical environments on the low frequency resistance fluctuations of single layer graphene field effect transistors. The shape of the power spectral density of noise was found to be determined by the energetics of the adsorption-desorption of molecules from the graphene surface making it the dominant source of noise in these devices. We also demonstrate a method of quantitatively determining the adsorption energies of chemicals on graphene surface based on noise measurements. We find that the magnitude of noise is extremely sensitive to the nature and amount of the chemical species present. We propose that a chemical sensor based on the measurement of low frequency resistance fluctuations of single layer graphene field effect transistor devices will have extremely high sensitivity, very high specificity, high fidelity, and fast response times. (c) 2015 AIP Publishing LLC.
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- 2015
12. Role of different scattering mechanisms on the temperature dependence of transport in graphene
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Kazi Rafsanjani Amin, Subroto Mukerjee, Aveek Bid, Suman Sarkar, Amandeep Singh, and Ranjan Modak
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Range (particle radiation) ,Multidisciplinary ,Materials science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Scattering ,Graphene ,Physics ,FOS: Physical sciences ,Low mobility ,Article ,law.invention ,symbols.namesake ,Electrical transport ,Impurity ,Chemical physics ,law ,Ionization ,Boltzmann constant ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,symbols - Abstract
Detailed experimental and theoretical studies of the temperature dependence of the effect of different scattering mechanisms on electrical transport properties of graphene devices are presented. We find that for high mobility devices the transport properties are mainly governed by completely screened short range impurity scattering. On the other hand, for the low mobility devices transport properties are determined by both types of scattering potentials - long range due to ionized impurities and short range due to completely screened charged impurities. The results could be explained in the framework of Boltzmann transport equations involving the two independent scattering mechanisms., Comment: Accepted for Publication in Scientific Reports, 2015
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- 2015
- Full Text
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13. High performance sensors based on resistance fluctuations of single layer graphene transistors
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Kazi Rafsanjani Amin and Aveek Bid
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Physics - Instrumentation and Detectors ,Materials science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Orders of magnitude (temperature) ,business.industry ,Graphene ,Physics ,Transistor ,FOS: Physical sciences ,Nanotechnology ,Instrumentation and Detectors (physics.ins-det) ,Noise (electronics) ,On resistance ,law.invention ,High fidelity ,law ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Optoelectronics ,General Materials Science ,Field-effect transistor ,Sensitivity (control systems) ,business - Abstract
One of the most interesting predicted applications of graphene monolayer based devices is as high quality sensors. In this letter we show, through systematic experiments, a chemical vapor sensor based on the measurement of low frequency resistance fluctuations of single layer graphene field-effect-transistor (SLG-FET) devices. The sensor has extremely high sensitivity, very high specificity, high fidelity and fast response times. The performance of the device using this scheme of measurement (which uses resistance fluctuations as the detection parameter) is more than two orders of magnitude better than a detection scheme where changes in the average value of the resistance is monitored. We propose a number-density fluctuation based model to explain the superior characteristics of noise measurement based detection scheme presented in this article.
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- 2015
- Full Text
- View/download PDF
14. Correlated Conductance Fluctuations Close to the Berezinskii-Kosterlitz-Thouless Transition in Ultrathin NbN Films
- Author
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Kazi Rafsanjani Amin, Siddhartha Kumar, John Jesudasan, R. Koushik, Mintu Mondal, Pratap Raychaudhuri, Aveek Bid, and Arindam Ghosh
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Condensed Matter::Quantum Gases ,Superconductivity ,Kosterlitz–Thouless transition ,Materials science ,Condensed matter physics ,Mean field theory ,Physics ,Condensed Matter::Superconductivity ,Phase (matter) ,General Physics and Astronomy ,Conductance ,Surface finish ,Kinetic energy - Abstract
We probe the presence of long-range correlations in phase fluctuations by analyzing the higher-order spectrum of resistance fluctuations in ultrathin NbN superconducting films. The non-Gaussian component of resistance fluctuations is found to be sensitive to film thickness close to the transition, which allows us to distinguish between mean field and Berezinskii-Kosterlitz-Thouless (BKT) type superconducting transitions. The extent of non-Gaussianity was found to be bounded by the BKT and mean field transition temperatures and depends strongly on the roughness and structural inhomogeneity of the superconducting films. Our experiment outlines a novel fluctuation-based kinetic probe in detecting the nature of superconductivity in disordered low-dimensional materials.
- Published
- 2013
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