Superconductor-insulator transition in the absence of disorder

Diamantini, M. C.; Trugenberger, Carlo A.; Vinokur, V. M.

doi:10.1103/physrevb.103.174516

“…Had the resulting state at temperature mK, been an Ohmic resistive state, where it is the velocity of charges which is proportional to the applied force rather than the charges’ acceleration, the above simple calculation shows that we would have expected the critical exponent , which is clearly not the case. Instead, for NbTiN, this state is a BTI 27 – 29 , with a topological gap for bulk excitations and charge transport mediated by the symmetry-protected edge modes 18 , 30 . Only at higher temperatures one would have observed a thermally activated bulk conductance.…”

Section: Resultsmentioning

confidence: 99%

Relaxation electrodynamics of superinsulators

Mironov

¹

,

Diamantini

²

,

Trugenberger

³

et al. 2022

Sci Rep

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Superinsulators offer a unique laboratory realizing strong interaction phenomena like confinement and asymptotic freedom in quantum materials. Recent experiments evidenced that superinsulators are the mirror-twins of superconductors with reversed electric and magnetic field effects. Cooper pairs and Cooper holes in the superinsulator are confined into neutral electric pions by electric strings, with the Cooper pairs playing the role of quarks. Here we report the non-equilibrium relaxation of the electric pions in superinsulating films. We find that the time delay $$t_{\mathrm {sh}}$$ t sh of the current passage in the superinsulator is related to the applied voltage V via the power law, $$t_{\mathrm {sh}}\propto (V-V_{\mathrm p})^{-\mu }$$ t sh ∝ ( V - V p ) - μ , where $$V_{\mathrm p}$$ V p is the effective threshold voltage. Two distinct critical exponents, $$\mu =1/2$$ μ = 1 / 2 and $$\mu =3/4$$ μ = 3 / 4 , correspond to jumps from the electric Meissner state to the mixed state and to the superinsulating resistive state with broken charge confinement, respectively. The $$\mu =1/2$$ μ = 1 / 2 value establishes a direct experimental evidence for the electric strings’ linear potential confining the charges of opposite signs in the electric Meissner state and effectively rules out disorder-induced localization as a mechanism for superinsulation. We further report the memory effects and their corresponding dynamic critical exponents arising upon the sudden reversal of the applied voltage. Our observations open routes for exploring fundamental strong interaction charge confinement via desktop experiments.

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“…Had the resulting state at temperature T = 20 mK, been an Ohmic resistive state, where it is the velocity of charges which is proportional to the applied force, rather than the charges' acceleration, the above simple calculation shows that we would have expected the critical exponent µ = 1, which is clearly not the case. Instead, for NbTiN, this state is a BTI [27][28][29], with a topological gap for bulk excitations and charge transport mediated by the symmetryprotected edge modes [18,30]. Only at higher temperatures one would have observed a thermally activated bulk conductance.…”

Section: Quantum Dissipationmentioning

confidence: 99%

Relaxation electrodynamics of superinsulators

Mironov¹,

Diamantini²,

Trugenberger³

et al. 2022

Preprint

Self Cite

0

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Superinsulators, realizing a single-color version of quantum chromodynamics, offer a unique laboratory for exploring the fundamentals of confinement and asymptotic freedom via desktop experiments. Recent experiments [1] evidenced that superinsulators are the mirror-twins of superconductors, with reversed electric and magnetic field effects. Cooper pairs and Cooper holes in the superinsulator are confined into neutral pions by electric strings, with the Cooper pairs playing the role of quarks [1,2]. Here we report the non-equilibrium relaxation of the electric pions in superinsulating films. We find that the time delay t sh of the current passage in the superinsulator is related to the applied voltage V via the power law, t sh ∝ (V − V p ) −µ , where V p is the effective threshold voltage. Two distinct critical exponents are found, µ = 1/2 and µ = 3/4, corresponding to jumps from the electric Meissner state to the mixed state and to the superinsulating resistive state with broken charge confinement, respectively. The exponent µ = 1/2 establishes a direct experimental evidence for the electric strings' linear potential confining the charges of opposite signs in the electric Meissner state. We further report memory effects and their corresponding dynamic critical exponents arising upon the sudden reversal of the applied voltage.

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“…In this phase, both charges and vortices are frozen in the bulk. The ground state wave function of this state has been derived in [29]; it consists of an integer-filling composite quantum incompressible fluid of charges and vortices at g = 1 with excess charges and vortices for g = 1 forming a Wigner crystal, with charges being in excess of vortices for g > 1 and vice versa.…”

Section: Adding Quantum Phase Slipsmentioning

confidence: 99%

Gauge Theories of Josephson Junction Arrays: Why Disorder Is Irrelevant for the Electric Response of Disordered Superconducting Films

Trugenberger

2023

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We review the topological gauge theory of Josephson junction arrays and thin film superconductors, stressing the role of the usually forgotten quantum phase slips, and we derive their quantum phase structure. A quantum phase transition from a superconducting to the dual, superinsulating phase with infinite resistance (even at finite temperatures) is either direct or goes through an intermediate bosonic topological insulator phase, which is typically also called Bose metal. We show how, contrary to a widely held opinion, disorder is not relevant for the electric response in these quantum phases because excitations in the spectrum are either symmetry-protected or neutral due to confinement. The quantum phase transitions are driven only by the electric interaction growing ever stronger. First, this prevents Bose condensation, upon which out-of-condensate charges and vortices form a topological quantum state owing to mutual statistics interactions. Then, at even stronger couplings, an electric flux tube dual to Abrikosov vortices induces a linearly confining potential between charges, giving rise to superinsulation.

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Superconductor-insulator transition in the absence of disorder

Cited by 15 publications

References 38 publications

Relaxation electrodynamics of superinsulators

Relaxation electrodynamics of superinsulators

Relaxation electrodynamics of superinsulators

Gauge Theories of Josephson Junction Arrays: Why Disorder Is Irrelevant for the Electric Response of Disordered Superconducting Films

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