Alternating superconductor-insulator transport characteristics in a quantum vortex chain

Abstract

Experimental studies of magnetoresistance in thin superconducting strips subject to a perpendicular magnetic field B exhibit a multitude of transitions, from superconductor to insulator and vice versa. Motivated by this observation, we study a theoretical model for the transport properties of a ladderlike superconducting device close to a superconductor-insulator transition. In this regime, strong quantum fluctuations dominate the dynamics of the vortex chain forming along the device. Utilizing a mapping of the vortex system at low energies to one-dimensional fermions at a chemical potential dictated by B, we find that a quantum phase transition of the Ising type occurs at critical values of the vortex filling, from a superconducting phase near integer filling to an insulator near half filling. The current-voltage (I-V) characteristics of the weakly disordered device in the presence of a d.c. current bias I is evaluated, and investigated as a function of B, I , the temperature T , and the disorder strength. In the Ohmic regime (I/e T ), the resulting magnetoresistance R(B) exhibits oscillations similar to the experimental observation. More generally, we find that the I-V characteristics of the system manifests a dramatically distinct behavior in the superconducting and insulating regimes.

Measurement of Critical Currents of Superconducting Aluminum Nanowires in External Magnetic Fields: Evidence for a Weber Blockade

“…The shape of the vortices and the configurations in which they can exist in a superconductor are strongly affected by the dimensions and the geometry of the sample [1][2][3][4][5][6][7][8][9][10][11]. In thin films, in which the penetration depth λ is larger than the film thickness d, vortices are of the Pearl type [2], and are shaped like pancakes.…”

“…Vortices cannot exist in nanowires that are narrower than the coherence length ξ [12], but if the width of a nanowire is on the order of a few ξ, vortices will be able to enter the nanowire in a single row. If the nanowire is also short enough that the energy difference between the states containing different number of vortices is significant, then an entry and an exit of a single vortex might be visible in transport measurements [7,[9][10][11]. Using charge-vortex duality [13], nanowires may exhibit Weber blockade for vortices [7], analogous to Coulomb blockade for electrons in quantum dots [14].…”

Spinful fermionic ladders at incommensurate filling: Phase diagram, local perturbations, and ionic potentials

“…We note that an analogous transition has recently been discussed in the context of the superconductorinsulator transition in superconducting quantum wires [111,112].…”

Vortex crossing, trapping, and pinning in superconducting nanowires of aNbSe2two-dimensional crystal

“…As we show below, in certain field ranges, the energy barrier determining the vortex crossing rate varies non-monotonically, giving rise to non-monotonic magnetoresistance variations in the nanowire. These magnetoresistance variations are distinct from the critical current oscillations observed in nanowires of disordered aluminum [26] and a:InO [27], which are due to the formation of a "Webber blockade" [28,29], wherein static vortices are added to a nanowire one at a time in analogy to the Coulomb blockade in quantum dots [30].…”