Vortex instability in molybdenum-germanium superconducting films

Liang, Manlai; Kunchur, Milind N.

doi:10.1103/physrevb.82.144517

Cited by 30 publications

(36 citation statements)

References 39 publications

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“…This prediction has been indeed observed in many different superconducting materials, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] thus demonstrating the universal character of this phenomenon. According to the LO model, the current density J * and the voltage V * at the point where the instability is triggered, are uniquely defined.…”

Section: Introductionmentioning

confidence: 53%

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

et al. 2015

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In 1976 Larkin and Ovchinnikov [Sov. Phys. JETP 41, 960 (1976)] predicted that vortex matter in superconductors driven by an electrical current can undergo an abrupt dynamic transition from a flux-flow regime to a more dissipative state at sufficiently high vortex velocities. Typically this transition manifests itself as a large voltage jump at a particular current density, so-called instability current density J * , which is smaller than the depairing current. By tuning the effective pinning strength in Al films, using an artificial periodic pinning array of triangular holes, we show that a unique and well defined instability current density exists if the pinning is strong, whereas a series of multiple voltage transitions appear in the relatively weaker pinning regime. This behavior is consistent with time-dependent Ginzburg-Landau simulations, where the multiple-step transition can be unambiguously attributed to the progressive development of vortex chains and subsequently phase-slip lines. In addition, we explore experimentally the magnetic braking effects, caused by a thick Cu layer deposited on top of the superconductor, on the instabilities and the vortex ratchet effect.

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Section: Introductionmentioning

confidence: 53%

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

et al. 2015

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“…[http://dx.doi.org/10.1063/1.4928285] Amorphous superconductors were first studied in detail in the early 1980s 1-3 and as a result of their weak pinning centres and homogeneity 4 have been of interest in a range of fields including studies of vortex stability 5 and flux avalanches. 6 Silicon-and germanium-based amorphous superconductors have attracted fresh interest due to their application in superconducting nanowire single photon detectors (SSPDs/SNSPDs).…”

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confidence: 99%

Amorphous molybdenum silicon superconducting thin films

et al. 2015

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Amorphous superconductors have become attractive candidate materials for superconducting nanowire single-photon detectors due to their ease of growth, homogeneity and competitive superconducting properties. To date the majority of devices have been fabricated using WxSi1−x, though other amorphous superconductors such as molybdenum silicide (MoxSi1−x) offer increased transition temperature. This study focuses on the properties of MoSi thin films grown by magnetron sputtering. We examine how the composition and growth conditions affect film properties. For 100 nm film thickness, we report that the superconducting transition temperature (Tc) reaches a maximum of 7.6 K at a composition of Mo83Si17. The transition temperature and amorphous character can be improved by cooling of the substrate during growth which inhibits formation of a crystalline phase. X-ray diffraction and transmission electron microscopy studies confirm the absence of long range order. We observe that for a range of 6 common substrates (silicon, thermally oxidized silicon, R- and C-plane sapphire, x-plane lithium niobate and quartz), there is no variation in superconducting transition temperature, making MoSi an excellent candidate material for SNSPDs.

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“…In this work we report transport measurements on amorphous MoGe films which are a good model system for investigating intrinsic flux dynamics because of their low bulk pinning and isotropic nature 8,9 . We observed a clear transition to a thermally-activated resistive state due to hopping of spontaneous perpendicular vortices, with the dynamics tuned by the pairbreaking effect of the parallel magnetic field.…”

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confidence: 99%

“…Our previous reviews and other papers [8][9][10][11] give further details about the measurement technique, thermal analysis, and parameter determination.…”

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confidence: 99%

Thermally activated dynamics of spontaneous perpendicular vortices tuned by parallel magnetic fields in thin superconducting films

2012

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We report magneto-transport measurements on a superconducting molybdenum-germanium (MoGe) film of thickness d=50 nm in parallel magnetic fields and show evidence of a transition from a Meissner state to a resistive state of spontaneous perpendicular vortices generated by thermal fluctuations above a certain temperature T > Tv (B). Here Tv appears to match the vortex core explosion condition d ≈ 4.4ξ(Tv), where ξ is the coherence length. For T > Tv, we observed that a nonlinear current-voltage (IV ) response (Ohmic at low currents and the power law V ∝ I β at higher I) is exponentially dependent on B 2 . We propose a model in which the resistive state at T > Tv is due to thermally-activated hopping of spontaneous perpendicular vortices tuned by the pairbreaking effect of the parallel B.

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Vortex instability in molybdenum-germanium superconducting films

Cited by 30 publications

References 39 publications

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

Amorphous molybdenum silicon superconducting thin films

Thermally activated dynamics of spontaneous perpendicular vortices tuned by parallel magnetic fields in thin superconducting films

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