Magnetic-Field-Tuned Quantum Phase Transition in the Insulating Regime of Ultrathin Amorphous Bi Films

Lin, Yen-Hsiang; Goldman, A. M.

doi:10.1103/physrevlett.106.127003

Cited by 25 publications

(17 citation statements)

References 27 publications

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“…Since the ρ xx maxima predicted by the standard HLN model (indicated by the blue curves) occur at a substantially lower B than those observed in experiments, ρ xx for B < B p cannot be solely described by spin-orbit coupling in the normal state and thus must be related to superconductivity. Such results are reminiscent of the intriguing influence of disorder on superconductivity27282930313233. In a disordered superconductor subject to a strong perpendicular magnetic field, insulating behavior can occur.…”

Section: Resultsmentioning

confidence: 92%

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Spin-orbit-coupled superconductivity

Lin

Wang

et al. 2014

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Superconductivity and spin-orbit (SO) interaction have been two separate emerging fields until very recently that the correlation between them seemed to be observed. However, previous experiments concerning SO coupling are performed far beyond the superconducting state and thus a direct demonstration of how SO coupling affects superconductivity remains elusive. Here we investigate the SO coupling in the critical region of superconducting transition on Al nanofilms, in which the strength of disorder and spin relaxation by SO coupling are changed by varying the film thickness. At temperatures T sufficiently above the superconducting critical temperature Tc, clear signature of SO coupling reveals itself in showing a magneto-resistivity peak. When T < Tc, the resistivity peak can still be observed; however, its line-shape is now affected by the onset of the quasi two-dimensional superconductivity. By studying such magneto-resistivity peaks under different strength of spin relaxation, we highlight the important effects of SO interaction on superconductivity.

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Section: Resultsmentioning

confidence: 92%

“…29), and Bi (ref. 31). Strong disorder, which is believed to be detrimental to superconductivity, plays a crucial role in maintaining superconductivity in such systems.…”

Section: Resultsmentioning

confidence: 99%

Spin-orbit-coupled superconductivity

Lin

Wang

et al. 2014

Sci Rep

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“…We will only focus on those models expected to be in the same universality class as our model (z ¼ 1); a more complete history can be found in Ref. [49] and the references therein.…”

Section: Appendix C: Universal Conductivity and Critical Exponentsmentioning

confidence: 99%

Dynamical Conductivity across the Disorder-Tuned Superconductor-Insulator Transition

et al. 2014

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We calculate the dynamical conductivity σðωÞ and the bosonic (pair) spectral function PðωÞ from quantum Monte Carlo simulations across clean and disorder-driven superconductor-insulator transitions (SITs). We identify characteristic energy scales in the superconducting and insulating phases that vanish at the transition due to enhanced quantum fluctuations, despite the persistence of a robust fermionic gap across the SIT. Disorder leads to enhanced absorption in σðωÞ at low frequencies compared to the SIT in a clean system. Disorder also expands the quantum critical region, due to a change in the universality class, with an underlying T ¼ 0 critical point with a universal low-frequency conductivity σ Ã ≃ 0.5ð4e 2 =hÞ.

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“…It has been found that even such samples exhibit a nonmonotonic magnetoresistance with a prominent peak resulting in a high-B phenomenology of the transport that is similar to their superconducting counterparts. 7,[21][22][23][24] We will refer to these samples as insulators, distinguishing them from the more standard superconductors.…”

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confidence: 99%

Superconducting correlations in thin films of amorphous indium oxide on the insulating side of the disorder-tuned superconductor-insulator transition

et al. 2012

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We study the magnetoresistance of an amorphous indium-oxide thin film whose disorder places it in the insulating side immediately after the disorder-tuned superconductor-insulator transition. We examine the magnetic field orientation dependence of the magnetoresistance and find both a pronounced insulating peak as a function of magnetic field and anisotropic behavior at low fields followed by high isotropy at higher fields, which both characterize highly disordered superconductors. Our findings establish a clear link between its low-field insulating phase and superconductivity.When a disordered superconducting thin film is subjected to a strong perpendicular magnetic field (B), it can undergo a transition into an unusual insulating state. 1,2 As B is increased, several regimes of resistance (R) are traversed. Initially, R increases as superconductivity is being weakened. This increase takes us through the superconductor-insulator transition (SIT) at the critical field B c and continues, at even higher rate, beyond the transition. In this, B-induced insulator R is nonmonotonic, reaching a maximum at B peak , which is followed by a sharp decrease of several orders of magnitude upon further increasing of B [see Fig. 1(a)].It turns out that when B is applied parallel with the film's surface, the magnetoresistance is similar to the more standard perpendicular-B orientation. There are, however, some important differences. To begin with, there is a shift of both B c and B peak 3 to higher values for parallel B. In a more detailed study of the angular dependence, 4 we found that the shift of both B c and B peak followed an angular dependence that highly corresponds with models pertinent to anisotropic superconductors. Additionally, although R is highly anisotropic at B < B peak , the anisotropy seems to vanish in the high-B regime.The strongly anisotropic nature of transport in the Binduced insulating regime, with its relation to superconducting models, is an important ingredient in support of the notion that the insulating peak beyond the SIT is strongly linked to superconductivity. 4-9 This notion is also supported by most theoretical groups that have attempted to account for the unusual insulating behavior. While they differ in the details of their approach, the common aspect in the majority of these works is that superconducting correlations survive the transition to the insulator and play a significant role in determining its transport properties. [10][11][12][13][14][15][16][17][18][19][20] If the disorder is further increased, the films will undergo a (B = 0) transition into an insulating phase. It has been found that even such samples exhibit a nonmonotonic magnetoresistance with a prominent peak resulting in a high-B phenomenology of the transport that is similar to their superconducting counterparts. 7,21-24 We will refer to these samples as insulators, distinguishing them from the more standard superconductors.The purpose of this communication is to establish a firm connection between the insulating behavior i...

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Magnetic-Field-Tuned Quantum Phase Transition in the Insulating Regime of Ultrathin Amorphous Bi Films

Cited by 25 publications

References 27 publications

Spin-orbit-coupled superconductivity

Spin-orbit-coupled superconductivity

Dynamical Conductivity across the Disorder-Tuned Superconductor-Insulator Transition

Superconducting correlations in thin films of amorphous indium oxide on the insulating side of the disorder-tuned superconductor-insulator transition

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