Anomalous heat capacities of niobium and tantalum below 1 K

Sellers, Gregory J.; Anderson, A. C.; Birnbaum, H.K.

doi:10.1103/physrevb.10.2771

Cited by 103 publications

(28 citation statements)

References 59 publications

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“…Anomalous behavior of the specific heat at low T Շ 1 K underpinned the two-gap notion, however this behavior was shown to be more likely associated with residual impurities. 21 Tunneling measurements were also noted to be very sensitive to oxidation of Nb at the interface. 22 With high-purity samples of resistance ratios R 275 K / R 9.3 K տ 1000, further investigations revealed no evidence of a second gap in ultrasonic attenuation 23 and thermodynamic measurements.…”

Section: Theory and Discussionmentioning

confidence: 99%

Structure and degeneracy of vortex lattice domains in pure superconducting niobium: A small-angle neutron scattering study

et al. 2009

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High-purity niobium exhibits a surprisingly rich assortment of vortex lattice ͑VL͒ structures for fields applied parallel to a fourfold symmetry axis, with all observed VL phases made up of degenerate domains that spontaneously break some crystal symmetry. Yet a single regular hexagonal VL domain is observed at all temperatures and fields parallel to a threefold symmetry axis. We report a detailed investigation of the transition between these lush and barren VL landscapes, discovering new VL structures and phase transitions at high fields. We show that the number and relative population of VL domains is intrinsically tied to the underlying crystal symmetry. We discuss how subtle anisotropies of the crystal may generate the remarkable VLs observed.

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Section: Theory and Discussionmentioning

confidence: 99%

Structure and degeneracy of vortex lattice domains in pure superconducting niobium: A small-angle neutron scattering study

et al. 2009

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“…Perinati et al, [15] observed that a large fraction of the energy thermalizes on a very long time scale (several milliseconds), and thus would not raise the temperature of the island. There has also been evidence for anomalous heat capacities in tantalum [16]. Finally, the measurements were performed in an ADR cryostat, and it is possible that trapped magnetic flux could result in normal-state zones, which would increase the tantalum heat capacity despite a magnetic shield surrounding the sample box.…”

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confidence: 99%

X-ray photon detection using superconducting resonators in thermal quasi-equilibrium

Quaranta

Cecil

Gades

et al. 2013

Supercond. Sci. Technol.

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Superconducting resonators have to date been used for photon detection in a non-equilibrium manner. In this paper, we demonstrate that such devices can also be used in a thermal quasiequilibrium manner to detect X-ray photons. We have used a resonator to measure the temperature rise induced by an X-ray photon absorbed in normal metal and superconducting absorbers on continuous and perforated silicon nitride membranes. We observed two distinct pulses with vastly different decay times. We attribute the shorter pulses to non-equilibrium quasiparticle relaxation and the longer pulses to a thermal relaxation process. In addition, we have measured the temperature dependence of the X-ray induced temperature rise and decay times. Finally, we have measured the resonator sensitivity and energy resolution. Superconducting resonators used in a thermal quasi-equilibrium manner have the potential to be used for X-ray microcalorimetry. a Electronic address: oquaranta@aps.anl.gov b Electronic address: amiceli@aps.anl.gov 1

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“…If we assume that the LSHA(I) is due to a Schottky-type excitation, then our specific heat data will follow the equation C = yT + fiT 3 + CSehottky (7) Referring to Fig. 12, the terms yT+flT 3 of Eq.…”

Section: Discussion Imentioning

confidence: 99%