Zero-bias anomaly in homogeneously disordered MoGe nanowires undergoing a superconductor-insulator transition

Kim, Hyun-Jeong; Rogachev, Andrey

doi:10.1103/physrevb.94.245436

Cited by 5 publications

(8 citation statements)

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“…This leads to a crossing of the I-V characteristics at high voltages for the narrower wires. At a magnetic field of 5 T, the differential conductance dI(V )/dV of the narrower strips displays a zero bias anomaly, i.e., a narrow dip around zero bias, similar to observations in MoGe nanowires [49]. The amplitude of the dip corresponds to the resistance increase below 1 K at such magnetic field (right column in Fig.…”

Section: Appendix B: Evolution Of I-v Characteristics With Decreasing Strip Widthsupporting

confidence: 80%

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Quantum phase slips and number-phase duality in disordered TiN nanostrips

et al. 2019

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We have measured the electric transport properties of TiN nanostrips with different widths. At zero magnetic field, the temperature-dependent resistance R(T ) saturates at a finite resistance toward low temperatures, which results from quantum phase slips in the narrower strips. We find that the current-voltage (I-V ) characteristics of the narrowest strips are equivalent to those of small Josephson junctions. Applying a transverse magnetic field drives the devices into a reentrant insulating phase, with I-V characteristics dual to those in the superconducting regime. The results provide evidence that our critically disordered superconducting nanostrips behave like small self-organized random Josephson networks.

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Section: Appendix B: Evolution Of I-v Characteristics With Decreasing Strip Widthsupporting

confidence: 80%

“…Similar to the data in Ref. [49], voltages around 100 μV at 35 mK are needed for an appreciable heating effect, corresponding to a current of 2 nA and a power input of 0.2 nW. Near the Bloch nose in Fig.…”

Section: Appendix B: Evolution Of I-v Characteristics With Decreasing Strip Widthsupporting

confidence: 70%

Quantum phase slips and number-phase duality in disordered TiN nanostrips

et al. 2019

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“…We recently showed that at high magnetic fields, where superconductivity is completely suppressed, the positive ZBA occurs due to electron heating. 46 The heating model semi-quantitatively explained both the height and width of the anomaly as well as its dependence on nanowire length. Moreover, in Ref.…”

Section: 4 B ≈ −mentioning

confidence: 96%

Deficiency of the scaling collapse as an indicator of a superconductor-insulator quantum phase transition

Rogachev

Sacépé

2020

Phys. Rev. B

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Finite-size scaling analysis is a well-accepted method for identification and characterization of quantum phase transitions (QPTs) in superconducting, magnetic and insulating systems. We formally apply this analysis in the form suitable for QPTs in 2-dimensional superconducting films to magnetic-field driven superconductor-metal transition in 1-dimensional MoGe nanowires. Despite being obviously inapplicable to nanowires, the 2d scaling equation leads to a high-quality scaling collapse of the nanowire resistance in the temperature and resistance ranges comparable or better to what is accepted in the analysis of the films. Our results suggest that the appearance and the quality of the scaling collapse by itself is not a reliable indicator of a QPT. We have also observed a sign-change of the zero-bias anomaly (ZBA) in the non-linear resistance, occurring exactly at the critical field of the accidental QPT. This behavior is often taken as an additional confirmation of the transition. We argue that in nanowires, the non-linearity is caused by electron heating and has no relation to the critical fluctuations. Our observation suggests that similar to the scaling collapse, the sign-change of ZBA can be a misleading indicator of QPT.Quantum phase transitions (QPT) occur at zero temperature between distinct ground states of matter; they are driven by a non-thermal parameter, g , which can be, for example, pressure or magnetic field. QPTs take place in many systems ranging from magnetic materials 1,2,3 and superconductors 4,5,6,7to cold atoms, 8 atomic nuclei 9,10 and stars. 11 The transition from one ground state to another can be of the first order, as in the case of clean metallic ferromagnets.12 It can also proceed by a smooth evolution of one-ground state to another over broad range of the driving parameter, as in the case of the crossover from Bardeen-Cooper-Schrieffer superconductivity to Bose-Einstein condensation.13 But, perhaps the most interesting is the case of continuous QPTs, which is characterized by the change of the ground state at certain critical value c

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“…For nanowire E, γ≈ 0.5, which corresponds to the correction caused by electron-electron interactions; for nanowire D a smaller value, γ≈ 0.27, was found, probably because this wire is not strictly in the 1D regime for normal electrons (w< L T ). At high bias the wires display a positive zero-bias anomaly (not shown) due to electron heating 26 . The critical behaviour described by equation (1) is associated exclusively with superconducting fluctuations.…”

Section: Corrected: Author Correctionmentioning

confidence: 99%

“…The details are given in the Supplementary Information. Some of the extracted parameters have previously been used to explain several phenomena in Mo-Ge nanowires 26,31 and films 32 . The analysis employed the scaling function computed in the theory 9 in a numerical form.…”

Section: Author Contributionsmentioning

confidence: 99%

Pair-breaking quantum phase transition in superconducting nanowires

et al. 2018

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Quantum phase transitions (QPT) between distinct ground states of matter are widespread phenomena [1][2][3][4][5] , yet there are only a few experimentally accessible systems 6,7 where the microscopic mechanism of the transition can be tested and understood. These cases are unique and form the experimentally established foundation for our understanding of quantum critical phenomena. Here we report that a magnetic-fielddriven QPT in superconducting nanowires-a prototypical one-dimensional system (d= 1)-can be fully explained by the critical theory 8,9 of pair-breaking transitions characterized by a correlation length exponent v≈1 and dynamic critical exponent z≈ 2. We find that in the quantum critical regime, the electrical conductivity is in agreement with a theoretically predicted scaling function and, moreover, that the theory quantitatively describes the dependence of conductivity on the critical temperature, field magnitude and orientation, nanowire crosssectional area, and microscopic parameters of the nanowire material. At the critical field, the conductivity follows a T Quantum phase transitions occur in many systems, including magnetic materials 1 , superconductors [13][14][15] , cold atomic gases 3 and also atomic nuclei 4 and stars 5. Similar to the thermal fluctuations in classical temperature-driven phase transitions, strong quantum fluctuations near the critical point of a QPT lead to the emergence of universal long-range behaviour, which can be common in very diverse systems. However, for a complete description of a QPT one must also identify and quantitatively incorporate into a theory specific microscopic processes which drive a system across the critical point and induce the fluctuations. Examples where such complete theories can be experimentally tested are scarce and include the two-channel Kondo effect in quantum dots 7 and Luttinger liquid behaviour in materials composed of weakly coupled one-dimensional (1D) spin-chains 6 . Superconducting systems present special interest in the context of QPTs because the fluctuations near the critical point can lead to the formation of unconventional superconducting phases (most notably this is one of the scenarios for high-temperature superconductivity in the cuprates 16 ). They also present a challenge-despite many years of efforts and overall success of phenomenological finite-size scaling analyses 2,13,14,17 , the microscopic mechanism of QPTs in 2d superconductors is still debated. In contrast, the physics of a QPT becomes much more transparent in 1D superconductors.Here we show that essentially all long-range and microscopic characteristics of a QPT driven in superconducting nanowires by a magnetic field can be described by a pair-breaking critical theory.A 1D superconductor can be defined as a wire with diameter smaller than π 2 1/2 ξ(0), where ξ(0) is the zero-temperature Ginzburg-Landau coherence length 18 . This condition ensures that vortices do not form within the wire and that the superconducting order parameter is approximately constant at a...

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Zero-bias anomaly in homogeneously disordered MoGe nanowires undergoing a superconductor-insulator transition

Cited by 5 publications

References 58 publications

Quantum phase slips and number-phase duality in disordered TiN nanostrips

Quantum phase slips and number-phase duality in disordered TiN nanostrips

Deficiency of the scaling collapse as an indicator of a superconductor-insulator quantum phase transition

Pair-breaking quantum phase transition in superconducting nanowires

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