Admittance of a long diffusive SNS junction

Abstract

The dynamical properties of hybrid normal metal/superconductor structures have recently come into research focus both experimentally and theoretically. Recent experimental studies of the coherent admittance Y (ω) of SNS rings as function of the phase difference φ0 are still not fully understood. Here we concentrate on the linear response regime, calculating Y (ω) by solving Usadel equations, linearised in electric field. Although partially reproducing previously known results, we find qualitatively different behaviour in the collisionless regime of τ −1 in ω E T h and high temperature T E T h and low temperature T E T h near the minigap closing φ0 ∼ π. We find that the dissipative part ReY (ω) peaks when the minigap closes (at a phase difference of π) even at high temperatures, when the equilibrium supercurrent is fully suppressed.

Alternating-current properties of short Josephson weak links

“…47. The admittance of long S-n-S junctions in the frequency range Ω ≪ E Th /ħ has been calculated in recent papers, 48,49 where an expression for Y (Ω) similar to Eq. (3) has been obtained.…”

Microwave Admittance of Gold‐Palladium Nanowires with Proximity‐Induced Superconductivity

“…[1,[10][11][12][13][14][15][16] In contrast, the near-equilibrium response of superconductor-normalmetal-superconductor (SNS) junctions to weak microwave radiation has become an active area of investigation only recently. [17][18][19][20][21] While the adiabatic contribution to the kinetic inductance can be calculated from the dc current-phase relation, at high frequencies both reactive and dissipative contributions arise also from other mechanisms, such as driven transitions between quasiparticle states and oscillation of the Andreev level populations. [18] Surprisingly, however, little experimental data has been published on the topic thus far.…”

“…[18] Surprisingly, however, little experimental data has been published on the topic thus far. [22,23] The parameter regimes and materials studied in the published experiments are very sparse, hence limiting the extent to which theoretical predictions [17][18][19][20][21] can be tested. In practice, data on the effective inductance and losses also expedites the process of designing high-frequency SNS-junction-based circuits, such as the SNS nanobolometer.…”

“…This is far below the estimated critical current of the SQUID chain. Furthermore, experimentally we ensured that we measured the linear response by making sure that the measured S 21 was not sensitive to factor-of-two changes in the measurement power.…”

“…As shown in Figure 2b,c the normalization procedure revealed clear Lorentzian-like lineshapes for S 21 , as one would expect for a resonator of this type. Raw ′ Φ = ( 0) 21 S and ′ Φ = ( 0.3) 21 S data are shown in Figure S3 of the Supporting Information for reference. Disentangling the SQUID chain response from the rest of the circuit is also aided by the fact that the SQUID chain is the only circuit element that responds to flux periodically, with a period that is identical for all of the identified resonances.…”