ترغب بنشر مسار تعليمي؟ اضغط هنا

Calorimetric readout of a superconducting proximity-effect thermometer

140   0   0.0 ( 0 )
 نشر من قبل Joonas Peltonen
 تاريخ النشر 2009
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

A proximity-effect thermometer measures the temperature dependent critical supercurrent in a long superconductor - normal metal - superconductor (SNS) Josephson junction. Typically, the transition from the superconducting to the normal state is detected by monitoring the appearance of a voltage across the junction. We describe a new approach to detect the transition based on the temperature increase in the resistive state due to Joule heating. Our method increases the sensitivity and is especially applicable for temperatures below about 300 mK.

قيم البحث

اقرأ أيضاً

63 - S. Tsuchiya , S. Tanda 2009
We report on the first observation of a novel type of superconducting proximity network using a superconductor-normal metal bilayer. Little-Parks oscillation measurements show that the superconducting current flows through a path enclosed by the edge rather than by the center of the Pb/Au wire in the network. Furthermore, several peaks were observed in a power spectrum analysis. We observed that the sequence of these peaks and that of the monolayer network were connected by the power function, which is a factor of the line width, S_{B_n} = alpha^{n-2}S_{A_n}. This suggests that even in a proximity network vortices are arranged in a way identical to a monolayer network.
102 - Jue Jiang , Weiwei Zhao , Fei Wang 2021
When a ferromagnet is placed in contact with a superconductor, owing to incompatible spin order, the Cooper pairs from the superconductor cannot survive more than one or two nanometers inside the ferromagnet. This is confirmed in the measurements of ferromagnetic nickel (Ni) nanowires contacted by superconducting niobium (Nb) leads. However, when a thin copper (Cu) buffer layer (3 nm, oxidized due to exposure to air) is inserted between the Nb electrodes and the Ni wire, the spatial extent of the superconducting proximity range is dramatically increased from 2 to a few tens of nanometers. Scanning transmission electron microscope images verify the existence of Cu oxides and the magnetization measurements of such a 3 nm oxidized Cu film on a SiO2/Si substrate and on Nb/SiO2/Si show evidence of ferromagnetism. One way to understand the long-range proximity effect in the Ni nanowire is that the oxidized Cu buffer layer with ferromagnetism facilitates the conversion of singlet superconductivity in Nb into triplet supercurrent along the Ni nanowires.
Interest in the superconducting proximity effect has recently been reignited by theoretical predictions that it could be used to achieve topological superconductivity. Low-T$_{c}$ superconductors have predominantly been used in this effort, but small energy scales of ~1 meV have hindered the characterization of the emergent electronic phase, limiting it to extremely low temperatures. In this work, we use molecular beam epitaxy to grow topological insulator Bi$_{2}$Te$_{3}$ in a range of thicknesses on top of a high-T$_{c}$ superconductor Fe(Te,Se). Using scanning tunneling microscopy and spectroscopy, we detect {Delta}$_{ind}$ as high as ~3.5 meV, which is the largest reported gap induced by proximity to an s-wave superconductor to-date. We find that {Delta}$_{ind}$ decays with Bi$_{2}$Te$_{3}$ thickness, but remains finite even after the topological surface states had been formed. Finally, by imaging the scattering and interference of surface state electrons, we provide a microscopic visualization of the fully gaped Bi$_{2}$Te$_{3}$ surface state due to Cooper pairing. Our results establish Fe-based high-T$_{c}$ superconductors as a promising new platform for realizing high-T$_{c}$ topological superconductivity.
The transport properties of a topological Josephson junction fabricated from a magnetically doped topological insulator (TI) were investigated. The conductance spectra of the Nb/Fe-Bi$_2$Te$_2$Se/Nb junction below 1 K showed an unusual trident-shaped zero-bias conductance peak with a tiny peak width of $sim$ 6 $mu$V. The central peak of the trident peak presents the dc-Josephson current, and the side peaks may reflect an induced unconventional Cooper pairing. Additionally, the critical currents followed inverse to temperature, which may also reflect the presence of an unconventional proximity effect. Furthermore, microwave irradiation derived a drastic change in the conductance spectra from the peak structure into oscillatory ones, a hallmark of the ac-Josephson supercurrent. The current-phase relation of the ac-Josephson effect under high power radiofrequency-irradiation was found to be 4$pi$-periodic. The results suggest that the junction based on magnetically doped 3D TIs may realize an unconventional Cooper pairing, thus enabling access to the basic physics of Majorana bound states and unconventional superconductivity.
We demonstrate the role of proximity effect in the thermal hysteresis of superconducting constrictions. From the analysis of successive thermal instabilities in the transport characteristics of micron-size superconducting quantum interference devices with a well-controlled geometry, we obtain a complete picture of the different thermal regimes. These determine whether the junctions are hysteretic or not. Below the superconductor critical temperature, the critical current switches from a classical weak-link behavior to one driven by the proximity effect. The associated small amplitude of the critical current makes it robust with respect to the heat generation by phase-slips, leading to a non-hysteretic behavior.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا