Properties of superconducting rf sputtered ultrathin films of Nb

Wolf, Stuart A.; Kennedy, James J.; Nisenoff, M.

doi:10.1116/1.568809

Cited by 103 publications

(36 citation statements)

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“…Reduction of T C in thin superconducting films was experimentally observed [7][8][9] and described in terms of the intrinsic proximity effect theory which was first suggested by Cooper [10] and generalized by Fominov and Feigel'man [11]. In the framework of this theory the NbN film is considered as a superconductor (S) sandwiched between two normal-metal (N) layers.…”

Section: Resultsmentioning

confidence: 99%

Structural, microchemical and superconducting properties of ultrathin NbN films on silicon

Schneider¹,

Freitag²,

Gerthsen

et al. 2009

Cryst. Res. Technol.

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Key words ultrathin NbN films, hot-electron bolometers, microstructure, transmission electron microscopy. PACS 68.37.Lp Structural, chemical and superconducting properties of thin NbN films used for development of fast and sensitive hot-electron bolometer (HEB) detectors for wide spectra range are reported. The thin NbN films with a thickness between 4 and 10 nm were deposited on the (001)Si substrates by magnetron sputtering. In order to investigate the film morphology and microchemistry, diffraction-contrast and high-resolution transmission electron microscopy (TEM) in combination with scanning TEM and electron energy loss spectroscopy (EELS) were performed. In addition, the zero-resistance critical temperature of the NbN films was measured and correlated to their thickness. The interrelations between fabrication conditions, crystalline and superconducting properties of the differently thick NbN films are discussed. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65th birthday

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Section: Resultsmentioning

confidence: 99%

Structural, microchemical and superconducting properties of ultrathin NbN films on silicon

Schneider¹,

Freitag²,

Gerthsen

et al. 2009

Cryst. Res. Technol.

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“…Figure 2(a) shows the T c variations with respect to V thickness. As expected, T c drops as the film thickness d s decreases, due to the reduction of electron density of states at the surface [19]. The degree of T c decrease is therefore inversely related to the film thickness under the assumption that there exists a thin inactive layer at the surface [20], in PRL 101, 137001 (2008) …”

mentioning

confidence: 93%

Infinite Magnetoresistance from the Spin Dependent Proximity Effect in Symmetry Drivenbcc−Fe/V/FeHeteroepitaxial Superconducting Spin Valves

2008

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Superconductivity in fully epitaxial bcc-Fe/V/Fe hybrid spin valve structures is influenced by the spin currents and supercurrents as well as band symmetry. The transition temperature is spin dependent in the presence of the proximity effect. A unique feature in this system is the band symmetry filtering taking place at the Fe/V interface. The absence of Delta2 Bloch states at the Fermi level in the Fe spin majority channel leads to spin selectivity and reduced transparency at the interface. Infinite magnetoresistance with clear remanence states is obtained, and implies the potential for spintronic applications.

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“…Superconducting properties of thin niobium films strongly depend on their thickness, purity and preparation conditions. 24,25,26,27,28,29 In order to compare our samples with those measured earlier, 24 termined T c of each film by the so called 90% criterion, i.e. the transition temperature was defined as the temperature where microwave absorption ∆(1/2Q) reaches 90% of its normal state value.…”

Section: Samplesmentioning

confidence: 99%

Microwave response of thin niobium films under perpendicular static magnetic fields

et al. 2006

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The microwave response of high quality niobium films in a perpendicular static magnetic field has been investigated. The complex frequency shift was measured up to the upper critical fields. The data have been analyzed by the effective conductivity model for the type-II superconductors in the mixed state. This model is found to yield consistent results for the coherence lengths in high-κ superconducting samples, and can be used with HTSC even at temperatures much below Tc. It is shown that for samples with high values of depinning frequency, one should measure both components of the complex frequency shift in order to determine the flow resistivity.The thick Nb film (160 nm) has low resistivity at 10 K, comparable to the best single crystals, and low κ value. In contrast, the thinnest (10 nm) film has κ ≈ 9.5 and exhibits a high depinning frequency (≈ 20 GHz). The upper critical field determined from microwave measurements is related to the radius of nonoverlaping vortices, and appears to be larger than the one determined by the transition to the normal state.

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Properties of superconducting rf sputtered ultrathin films of Nb

Abstract: Effects of rf bias on the superconducting and structural properties of rf magnetron sputtered NbN J. Appl. Phys. 59, 2905 (1986); 10.1063/1.336950 rf superconducting properties of reactively sputtered NbN

Cited by 103 publications

References 0 publications

Structural, microchemical and superconducting properties of ultrathin NbN films on silicon

Structural, microchemical and superconducting properties of ultrathin NbN films on silicon

Infinite Magnetoresistance from the Spin Dependent Proximity Effect in Symmetry Drivenbcc−Fe/V/FeHeteroepitaxial Superconducting Spin Valves

Microwave response of thin niobium films under perpendicular static magnetic fields

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