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We study anomalous mesoscopic transport effects at the onset of the superconducting transition focusing on the observed large Nernst-Ettinghausen signal in disordered thin films. In the vicinity of the transition, as the Ginzburg-Landau…

Superconductivity · Physics 2019-05-15 Mengling Hettinger , Maxim Khodas , Alex Levchenko

We report a theoretical investigation on conductance fluctuation of mesoscopic systems. Extensive numerical simulations on quasi-one dimensional, two dimensional, and quantum dot systems with different symmetries (COE, CUE, and CSE)…

Disordered Systems and Neural Networks · Physics 2009-10-20 Zhenhua Qiao , Yanxia Xing , Jian Wang

Quantum interference effects such as weak localization (WL) and universal conductance fluctuations (UCF) normally yield consistent electronic phase-coherence lengths in homogeneous conductors. Here we show that in individual carbon nanotube…

Universal conductance fluctuations (UCF) are a hallmark of quantum interference in mesoscopic devices. According to the Altshuler-Lee-Stone theory, the amplitude of UCF remains independent of system parameters such as Fermi energy and…

Mesoscale and Nanoscale Physics · Physics 2025-06-11 Qiang Yang , Yayun Hu , Zhe Hou , Peiqing Tong

We study the effect of mesoscopic fluctuations on the validity of the Wiedemann--Franz (WF) law for quasi-one-dimensional metal wires and open quantum dots. At temperatures much less than the generalized Thouless energy, E_c, the WF law is…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Maxim G. Vavilov , A. Douglas Stone

We report a systematic experimental study of mesoscopic conductance fluctuations in superconductor/normal/superconductor (SNS) devices Nb/InAs-nanowire/Nb. These fluctuations far exceed their value in the normal state and strongly depend on…

Mesoscale and Nanoscale Physics · Physics 2009-12-18 T. S. Jespersen , M. L. Polianski , C. B. Soerensen , K. Flensberg , J. Nygaard

We have measured the low frequency (1mHz<f<10Hz) resistance fluctuations in metallic nanowires (diameter 15nm to 200nm) in the temperature range 77K to 400K. The nanowires were grown electrochemically in polycarbonate membranes and the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Aveek Bid , Achyut Bora , A. K. Raychaudhuri , D. Chakravortya

We perform a multifractal detrended fluctuation analysis of the magnetoconductance data of two standard types of mesoscopic systems: a disordered nanowire and a ballistic chaotic billiard, with two different lattice structures. We observe…

Mesoscale and Nanoscale Physics · Physics 2021-12-08 N. L. Pessoa , A. L. R. Barbosa , G. L. Vasconcelos , A. M. S. Macêdo

In this paper we report the measurement of conductance fluctuations in single crystals of Si made metallic by heavy doping (n \approx 2-2.5n_c, n_c being critical composition at Metal-Insulator transition). Since all dimensions (L) of the…

Disordered Systems and Neural Networks · Physics 2009-10-31 Arindam Ghosh , A. K. Raychaudhuri

We study the influence of thermal fluctuations on the magnetic behavior of square mesoscopic superconductors. The strength of thermal fluctuations are parameterized using the Ginzburg number, which is small ($G_i \approx 10^{-10}$) in…

Superconductivity · Physics 2009-11-11 Alexander D. Hernandez , B. J. Baelus , Daniel Dominguez , F. M. Peeters

We examine universal conductance fluctuations (UCFs) in mesoscopic normal-superconducting-normal (N-S-N) structures using a numerical solution of the Bogoliubov - de Gennes equation. We discuss two cases depending on the presence (``open''…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Tero T. Heikkila , Martti M. Salomaa , C. J. Lambert

We demonstrate the presence of energy dependent fluctuations in the localization length, which depend on the disorder distribution. These fluctuations lead to Ensemble Averaged Conductance Fluctuations (EACF) and are enhanced by large…

Disordered Systems and Neural Networks · Physics 2009-11-13 M. Hilke

Universal conductance fluctuations (UCFs) are extracted in the magnetoresistance responses in the bulk-insulating Bi2Te2Se microflakes. Its two-dimensional character is demonstrated by the field-tilting magnetoresistance measurements. Its…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Zhaoguo Li , Yuze Meng , Jian Pan , Taishi Chen , Xiaochen Hong , Shiyan Li , Xuefeng Wang , Fengqi Song , Baigeng Wang

Fluctuations are important near phase transitions, where they can be difficult to describe quantitatively. Superconductivity in mesoscopic rings is particularly intriguing because the critical temperature is an oscillatory function of…

Superconductivity · Physics 2009-01-06 Nicholas C. Koshnick , Hendrik Bluhm , Martin E. Huber , Kathryn A. Moler

Influence of equilibrium thermal 1/f-type mobility fluctuations on time-of-flight measurements is considered. We show that it can explain experimental time dependencies of transient photocurrents.

Materials Science · Physics 2010-08-27 Yuriy E. Kuzovlev

We measured the low frequency (10mHz < f < 10Hz) resistance fluctuations (Noise) in single crystalline ferromagnetic Ni nanowires (diameter ~35nm) in the temperature range 80K-300K. The noise spectral power shows 1/f dependence. The…

Mesoscale and Nanoscale Physics · Physics 2009-06-24 Sudeshna Samanta , M. Venkata Kamalakar , A. K. Raychaudhuri

In the commented work (PRL 109, 187005 (2012)), Rullier-Albenque et al. present measurements of transverse magnetoresistivity above the transition temperature Tc in clean LiFeAs. By analyzing their data, these authors conclude that the…

Superconductivity · Physics 2015-09-25 A. Ramos-Álvarez , J. Mosqueira , F. Vidal

Quantum coherence of electrons in ferromagnetic metals is difficult to assess experimentally. We report the first measurements of time-dependent universal conductance fluctuations in ferromagnetic metal (Ni$_{0.8}$Fe$_{0.2}$) nanostructures…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 S. Lee , A. Trionfi , D. Natelson

Quantum coherence of electrons can produce striking behaviors in mesoscopic conductors, including weak localization and the Aharonov-Bohm effect. Although magnetic order can also strongly affect transport, the combination of coherence and…

Mesoscale and Nanoscale Physics · Physics 2023-08-03 Molly P. Andersen , Evgeny Mikheev , Ilan T. Rosen , Lixuan Tai , Peng Zhang , Kang L. Wang , Marc A. Kastner , David Goldhaber-Gordon

Progressive reduction of the effective diameter of a nanowire is applied to trace evolution of the shape of superconducting transition $R(T)$ in quasi-one-dimensional aluminum structures. In nanowires with effective diameter $\leq$ 15 nm…

Superconductivity · Physics 2009-11-13 M. Zgirski , K. -P. Riikonen , V. Touboltsev , K. Yu. Arutyunov