Metal-Insulator Transition in Granular Aluminum

Dynes, R. C.; Garno, J. P.

doi:10.1103/physrevlett.46.137

Cited by 196 publications

(73 citation statements)

References 11 publications

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“…The frequency-dependent absorptive responsivity R(ω) can then also be estimated [7]. Measurements of the bolometer resistance-current calibration curves for a discrete set of bath temperatures ( Figure 2 shows one at T=1.759 K) have been collected using a 4-wire technique, and the transition temperature is near 1.8 K, in agreement with previous investigations of the superconductivity of GA alone [13]. The Pd capping layer is apparently sufficiently thin that there is no substantial suppression of the SC transition of the underlying GA layer due to the proximity effect [14].…”

Section: Characterization Of the Sc Ga/pd Bilayer Microbolometerssupporting

confidence: 83%

Fabrication of robust superconducting granular aluminium/palladium bilayer microbolometers with sub-nanosecond response

Wilson

2007

J. Phys.: Conf. Ser.

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Abstract. We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer's characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution algorithm of Edwards et al. [2] to obtain the phonon flux in a heat pulse experiment with nanosecond resolution.

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Section: Characterization Of the Sc Ga/pd Bilayer Microbolometerssupporting

confidence: 83%

Fabrication of robust superconducting granular aluminium/palladium bilayer microbolometers with sub-nanosecond response

Wilson

2007

J. Phys.: Conf. Ser.

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“…These corrections have been observed in tunneling studies of the DOS in disordered metals in 3D [3] and 2D [4,5]. In the strongly insulating regime, Efros and Shklovskii (ES) have predicted [6,7] that Coulomb interactions lead to a soft Coulomb gap in the single-particle DOS, with a vanishing DOS at the Fermi level.…”

mentioning

confidence: 93%

“…In the weakly disordered limit, Altshuler et al [1] have predicted that interactions lead to a singular depletion of the DOS with a |ǫ| 1/2 dependence in three dimensions (3D) and a ln|ǫ| dependence [2] in two dimensions(2D), where ǫ is the energy measured from the Fermi level. These corrections have been observed in tunneling studies of the DOS in disordered metals in 3D [3] and 2D [4,5]. In the strongly insulating regime, Efros and Shklovskii (ES) have predicted [6,7] that Coulomb interactions lead to a soft Coulomb gap in the single-particle DOS, with a vanishing DOS at the Fermi level.…”

mentioning

confidence: 93%

Hard Correlation Gap Observed in Quench-Condensed Ultrathin Beryllium

Bielejec

Ruan

2001

Phys. Rev. Lett.

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We report on the tunneling density of states (DOS) in ultrathin and strongly disordered Be films quench-condensed at 20 K. Above 5 K, the DOS shows the well-known logarithmic anomaly at the Fermi level. Only in a narrow temperature range near 2 K is the DOS linearly dependent on energy, as predicted by Efros and Shklovskii. However, both the zero-bias conductance and the slope of the linear DOS are found to decrease drastically with decreasing temperature. Tunneling measurements at mK temperatures have revealed conclusively that a hard correlation gap opens up in the DOS.PACS numbers: 73.40. Gk, 72.15.Rn, 71.30.+h, 74.40+k It is known that electron-electron (e-e) Coulomb interactions can drastically alter the density of states (DOS) near the Fermi energy in disordered electronic systems. In the weakly disordered limit, Altshuler et al.[1] have predicted that interactions lead to a singular depletion of the DOS with a |ǫ| 1/2 dependence in three dimensions (3D) and a ln|ǫ| dependence [2] in two dimensions(2D), where ǫ is the energy measured from the Fermi level. These corrections have been observed in tunneling studies of the DOS in disordered metals in 3D [3] and 2D [4,5]. In the strongly insulating regime, Efros and Shklovskii (ES) have predicted [6,7] that Coulomb interactions lead to a soft Coulomb gap in the single-particle DOS, with a vanishing DOS at the Fermi level. This soft gap is quadratic in energy in 3D and linear in energy in 2D. In both 2D and 3D, the Coulomb gap is predicted [7] to lead to a variable-range hopping resistance of R ✷ (T) = R 0 exp [(T 0 /T ) ν ], where ν = 1/2 and T is the temperature.Although it was predicted over two decades ago, the Coulomb gap is by no means an understood subject. The existence of the ES Coulomb gap had mainly been inferred from transport experiments such as glassy electronic relaxation [8] and hopping conduction [9,10]. The ES Coulomb gap in 3D was directly observed a few years ago by tunneling in Si:B [11]. Direct evidence for the ES Coulomb gap in 2D has been reported only during the past year by Butko et al. [12], but no temperature dependence and magnetic field dependence have been reported. The Coulomb gap predicted by Efros and Shklovskii [6,7] describes the DOS for adding an extra electron to the ground state without allowing relaxation. Later theoretical studies [13] of the Coulomb gap, taking into consideration multi-electron processes, have found a further reduction of the DOS near the Fermi energy, leading to a much harder gap with effectively no states within a narrow but finite range of energy. In fact, a change in the hopping exponent with decreasing temperature from ν = 1/2 to ν = 1 was reported a few years ago in Si:B[10], suggesting that a hard gap might exist at low temperatures. Most recently, the Coulomb gap in 2D has become a subject of renewed interest [14] with the unexpected discovery of a metal-insulator transition in the 2D electron gas in semiconductor devices [15].

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“…3(b), clearly showing a nonmetallic transport behavior ‫ץ͑‬ / ‫ץ‬T Ͻ 0͒ down to 4 K. This type of conduction behavior has been observed in a wide variety of disordered materials, in which the resistance curves were fitted to a variable range hopping (VRH) model. [14][15][16][17][18][19] The R / T curve of Fig. 3(b) was indeed successfully fitted to a three-dimensional (3D) VRH model, described in Eq.…”

Section: A the Fib Contact Contribution To The Measured Resistancementioning

confidence: 99%

Probing intrinsic transport properties of single metal nanowires: Direct-write contact formation using a focused ion beam

Marzi¹,

Iacopino²,

Quinn³

et al. 2004

Journal of Applied Physics

106

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Access to the full text of the published version may require a subscription. Probing intrinsic transport properties of single metal nanowires: Direct-write contact formation using a focused ion beam The transport characteristics of 70-nm-diameter platinum nanowires (NWs), fabricated using a pore-templated electrodeposition process and individually contacted using a focused ion beam (FIB) method, are reported. This approach yields nanowire devices with low contact resistances ͑ϳ400 ⍀͒ and linear current-voltage characteristics for current densities up to 65 kA/ cm 2 . The intrinsic nanowire resistivity ͑33± 5 ⍀ cm͒ indicates significant contributions from surface-and grain-boundary scattering mechanisms. Fits to the temperature dependence of the intrinsic NW resistance confirm that grain-boundary scattering dominates surface scattering (by more than a factor of 2) at all temperatures. Our results demonstrate that FIB presents a rapid and flexible method for the formation of low-resistance ohmic contacts to individual metal nanowires, allowing intrinsic nanowire transport properties to be probed. Rights

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Metal-Insulator Transition in Granular Aluminum

Cited by 196 publications

References 11 publications

Fabrication of robust superconducting granular aluminium/palladium bilayer microbolometers with sub-nanosecond response

Fabrication of robust superconducting granular aluminium/palladium bilayer microbolometers with sub-nanosecond response

Hard Correlation Gap Observed in Quench-Condensed Ultrathin Beryllium

Probing intrinsic transport properties of single metal nanowires: Direct-write contact formation using a focused ion beam

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