57 research outputs found
Weak localization in superconductors: A study of radiation-damaged Nb_3Ir
We have studied the critical temperature T_c, upper critical field, and magnetotransport variation as a function of radiation damage in the low-T_c A15 superconductor Nb_3Ir. We find a nonmonotonic variation in Tc with disorder and analyze these results in terms of the competition between density-of-states effects and weak localization. Magnetoresistance measurements confirm the presence of electron interaction effects associated with weak localization
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Brillouin scattering: its application to the study of damage and amorphization
A brief review of Brillouin scattering is made emphasizing its advantages and disadvantages over conventional ultrasonic techniques. One of its advantages is that the elastic properties of very thin films (approx. 1..mu..) can be investigated. The authors have used this technique to study changes in shear elastic constants of materials irradiated with high energy ions. These particles only penetrate approx. 1..mu.. into the material but produce very high defect concentrations which, in certain cases, can lead to amorphization. In Nb/sub 3/Ir and Zr/sub 3/Al very large changes are observed before the onset of amorphization, while in Si the changes occur concomitantly with amorphization. The significance of the hardening observed in Zr/sub 3/Al when it becomes amorphous will be discussed
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Dissipation in high-temperature superconductors in a magnetic field
The absence of a Lorentz force dependence on dissipation in the highly anisotropic highly high-temperature superconductor, Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub x}, has been measured over a wide range of current densities in broadened resistive transitions, current-voltage characteristics, magnetoresistances, and critical current densities, J{sub c}. The magnetoresistances are very useful to find out the correct temperature and field dependences of the activation energy. As an alternative to flux motion, we consider a Josephson-coupling model which is consistent with the broadened resistive transitions and the lack of Lorentz-force dependence. We found that the Josephson-coupling model agrees with the temperature dependences of the activation energy and J{sub c} and is better matched to the weak field dependence of J{sub c} than the flux creep model. Possible origins of Josephson junctions in high-quality films and single crystals are discussed. 12 refs., 6 figs
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Superconducting notch filter
Results of a preliminary investigation of a superconducting notch filter for possible application in the 2 to 30 MHz high frequency (HF) communication band are presented. The circuit was successfully implemented using planar geometry so that closed cycle refrigeration could be used to cool circuits fabricated from high T/sub c/ Nb/sub 3/Sn or Nb/sub 3/Ge thin films. In the present design, circuit Q's of about 2 x 10/sup 3/ were obtained with 50-ohm source and output impedance. (TFD
Populism and feminist politics: The cases of Finland and Spain
While populism has been subject to growing scholarly interest, its relationship to feminist politics has remained conspicuously understudied. This article investigates this relationship by analysing two cases of European populism: left populism in Spain (Podemos), and right populism in Finland (the Finns Party). The questions asked, and the challenges posed to feminist politics from populist political forces are intriguing: How is feminist politics articulated in both left and right populism? What differences can be discerned between left and right populism for feminist politics? To explore this, the article analyses three core dimensions: (1) political representation: descriptive representation (numbers of women, men and minority positions) and substantive representation (policy content in relation to gender equality); (2) populist partiesâ formal and informal gender institutions such as internal quotas, gender equality plans and institutional culture; and (3) dedicated spaces for feminist politics such as womenâs sections or feminist groups. It is argued that political ideology matters for feminist politics, and while left parties are more responsive to feminist concerns and populism poses specific problems for feminist politics, it is the gendered culture of political parties that ensures both left and right parties are problematic for feminist politics
âRepeal the 8thâ in a Transnational Context: The Potential of SRHRs for Advancing Abortion Access in El Salvador
This article undertakes a discursive feminist reading of citizenship and human rights to understand, through the cases of Ireland and El Salvador, domestic abortion rights movements as part of a transnational womenâs rights movement. While abortion has been partially decriminalised in Ireland, approximately 42 per cent of the worldâs women1 of reproductive age still live in a country where abortion is prohibited entirely or only permitted to save a womanâs life or health (Singh et al., 2018, p. 4). In El Salvador, abortion is illegal and those suspected of having the procedure are prosecuted. As in Ireland, since 2012/2013 numerous controversies have brought the issue to wider public attention and have further galvanised the feminist movement to campaign for reform. Feminist abortion rights campaigns in both countries have connected important sites of activism and contestation: civil society, national parliaments, regional human rights systems and the United Nations
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High field properties of NbN ribbon conductors
This paper reports the first high field measurements on ribbon conductors composed of NbN and Cu deposited onto Hastelloy ribbons. These ribbons are 5 to 8 cm long, 1/8'' wide, and have several microns of NbN, covered with several microns of Cu, deposited onto one side. Such samples have a T/sub c/ approx. 14.5 K, H/sub c2/ (2.0 K) approx. 26 T in the parallel direction and J/sub c/ (20 T, 2.0 K) up to 3 x 10/sup 4/ A/cm/sup 2/
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Argonne National Laboratory Reports
The design of a tunable high-Q superconducting notch filter is presented. The filter is designed to be manufactured from high Tc superconductors (Nb3S, Nb3Ge) made by high-rate magnetron sputtering on sapphire substrates. The geometry of the various elements, holder materials for the cryostat, studies relating to the preparation of suitable high Tc materials, and the photo-etching procedures for the filter elements are discussed
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