Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S27: Superconductivity:Devices & Materials-I |
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Sponsoring Units: DCMP Chair: Hong-Yi Xie, University of Oklahoma Room: Room 219 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S27.00001: Performance of Epoxy-Impregnated High Temperature Superconducting (HTS) Coils Inside a 16 Tesla Large Bore, Low Temperature Superconducting (LTS) Magnet Jeremy Good This paper presents the design, construction and test results of HTS insert coil sets made of YBCO/BSCCO conductors. The HTS insert coils are designed to produce a field of up to 6 T to 9 T at 4 K in a 110 mm bore in a background magnet of 16T. The coils use over 2.5 km of 4 mm- wide Second Generation (2G) HTS conductors provided by Sumitomo Electric, Fujikura and others. The coil set, when inside the 16 T LTS outset, generates a combined field of up to 25 T and provide a practical magnet for research use. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S27.00002: Ion irradiation as a wafer-scale method for amorphizing superconducting thin films Katja V Kohopää, Alberto Ronzani, Robab Najafi Jabdaraghi, Arijit Bera, Mario Ribeiro, Dibyendu Hazra, Emma Mykkänen, Jorden Senior, Mika Prunnila, Janne Lehtinen, Antti Kemppinen Nanoscale superconducting structures, such as nanowires, have several promising applications in quantum technology. The nanostructures can become irreproducible when the dimensions are comparable with the grain sizes of the material. One possible solution is to use amorphous materials. We demonstrate ion irradiation as a wafer-scale method for the fabrication of amorphous superconducting thin films [1]. We study the ion irradiation treatment using argon or gallium ions on single-element and compound materials. We characterize the properties of the films with transmission electron microscopy imaging and electrical transport measurements. Our results indicate that gallium and argon ions increase disorder in the thin films in qualitatively similar manner - they destroy the grain structure, increase the resistivity, and alter the superconducting transition temperature. However, our results show that argon tends to form gas pockets that can be detrimental for certain applications, whereas gallium ion irradiation allows to produce a thin, uniform, and amorphous film that is promising, e.g., for superconducting nanowire single-photon detectors. |
Thursday, March 9, 2023 8:24AM - 8:36AM |
S27.00003: Implementing Josephson Junction spectroscopy in a scanning tunneling microscope Margaret Fortman, Zachary J Krebs, Ramiro H Rodriguez, David C Harrison, Wyatt A Behn, Robert McDermott, Caglar Girit, Victor W Brar Josephson junction spectroscopy (JJS) is a powerful local microwave spectroscopy technique that has promising potential as a diagnostic tool to probe the microscopic origins of noise in superconducting qubits. In this talk I will present progress towards realizing JJS in a scanned geometry, where the Josephson junction (JJ) is formed between a superconducting sample and a high capacitance superconducting STM tip. I will first present data from planar Nb-based JJs that demonstrates the benefits of including a high capacitance shunt across the JJ, which improves spectral resolution. It will then be shown how an equivalent circuit can be implemented by utilizing a planarized STM tip with local prominences, which is fabricated via electron beam lithography and reactive ion etching, followed by coating with a superconducting layer. I will then show the results of initial measurements that utilize these high capacitance tips to probe Niobium Nitride (NbN) substrates, and I will discuss the effects of different circuit geometries (i.e. preamp and filter choice) on those measurements. Finally, calculations will be shown that estimate the sensitivity and spectral resolution of this scanned JJS technique. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S27.00004: Observation of multiple Andreev-re ection assisted cooling eects in a nano superconducting Josephson junctions SHUNG-KANG KOH We demonstrate the cooling eect induced by multiple Andreev-reflection (MAR) in the thermal hysteresis of superconducting constrictions in a clean and short limit. We measure the current-voltage (I - V ) characteristics of a single constriction and micro-SQUID device, and observe the voltage-step jumps above the critical current (Ic) and below the gap (Δ). Our analysis shows that the voltage-steps taken place over Ic are related to the dynamic phase-slip, but within Δ are induced by MAR. To demonstrate the cooling effect, we show the co-existence of MAR and quantum interference in the retrapping currents in a micro-SQUID device. Our findings provide a unified picture to understanding nonequilibrium superconductivity, and have strong implications in developing superconducting ballistics devices. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S27.00005: Superconducting Nanowire Devices and their Performance in Magnetic Fields Tomas Polakovic, Volodymyr G Yefremenko, Timothy J Draher, John Pearson, Alan M Dibos, Yi Li, Rosalba A Huerta, Jidong S Jiang, Whitney R Armstrong, Zein-Eddine Meziani, Valentine Novosad Devices based on superconducting nanowires, such as single photon detectors and cryotron logic devices, have been proposed for applications in many fields, e.g., for information transfer in quantum communication, particle detection in nuclear and high energy physics and imaging in medical fields. One of the open questions related to their long-term and large-scale viability in these applications is their ability to perform in external magnetic fields. |
Thursday, March 9, 2023 9:00AM - 9:12AM |
S27.00006: Why shot noise usually cannot detect pairing in mesoscopic superconducting tunneling devices Jiasen Niu, Koen M Bastiaans, John Jesudasan, Pratap Raychaudhuri, Milan P Allan Shot noise is a powerful tool for determining the effective charge in mesoscopic systems. It can detect electron pairing in superconductors, where shot noise changes from q=1e noise to q=2e noise. Here, I will present our shot noise results in typical mesoscopic superconductor-insulator-superconductor junctions using our newly developed low temperature noise amplifier. Our results indicate that the shot noise does not reflect the q=2e superconducting state but instead stays at a level corresponding to single electron charges, q = 1e. I will show that this is caused by the fact that the large number of low-transparency channels obscure the shot noise from q=2e process. Our results indicate that the typical transparencies in mesoscopic junctions will suppress the q=2e shot noise and that controlling the transparency is key for detecting pairing in mesoscopic superconducting junctions. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S27.00007: Tunable Superconductor Insulator Transition in a Quantum Phase Slip Interference Device Jan Nicolas Voss, Micha Wildermuth, Maximilian Kristen, Hannes Rotzinger, Alexey V Ustinov The duality between quantum phase slip nanowires and Josephson junctions has triggered a variety of theoretical and experimental works. However, many aspects of these fluctuations are still not fully understood, especially when interference effects are considered. |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S27.00008: EXAFS study of clustering of Mn in Al-Mn based transition edge sensor Ghadendra B Bhandari, Thomas R Stevenson, Emily M Barrentine, Mikel B Holcomb Transition edge sensors are designed for space exploration by offering high spectral resolving power over a broad band with miniaturized size. A key enabling component for such kind of sensor will be microwave kinetic inductance detectors (MKIDs). The MKID contains the superconducting resonator that responds to thermal fluctuation from radiation input. The Al-Mn alloy based detectors developed by NASA Goddard are favorably showing the shifting of the critical temperature. The detectors, annealed at higher temperature, are tending to decrease critical temperature Tc. Using extended x-ray absorption fine spectroscopy (EXAFS), we studied clustering of the Mn dopants in Al. We found that the clustering of Mn increases with increasing annealing temperature. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S27.00009: Epitaxial, Silicon-Compatible CoSi2 Thin Film SQUID with Constriction-Type Junction Ruoshui Li, Yichen Jia, Anthony T Bollinger, Kim Kisslinger, Mingzhao Liu, Charles T Black, Christian Lavoie, Vesna Stanic, Tharanga Nanayakkara Transition metal silicides are widely used in integrated circuits as contacts and interconnect. CoSi2 has superconducting Tc of 1.4 K and lattice mismatch to Si of 1.2%, thus making it promising for integrating silicon technology into superconducting device fabrication. Here we demonstrate the growth of epitaxial CoSi2 thin film on Si(111) substrate and the fabrication of a constriction-type superconducting quantum interference device (SQUID) by silicidation of Co metal on the silicon substrate. The CoSi2 -Si interface shows CoSi2 (111) // Si(111) epitaxy, with in-plane texture CoSi2 (100) // Si(111) and CoSi2(110) // Si(111). The fabricated SQUID has a superconducting loop area of 0.8 μm2, the oscillating critical current with the applied magnetic field typical for SQUID is observed with φ0 = 1.3 mT. The junction resistance of constriction-type SQUID is calculated to be linear with device channel length. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S27.00010: Thermoelectric effects in superconductor-ferromagnetic heterostructures Portia J Allen, Kirsten E Blagg, Meenakshi Singh Superconductor-ferromagnetic (S-F) heterostructures have been predicted to show significant thermoelectric effects at cryogenic temperatures. Superconductors have a poor thermoelectric figure of merit (zT) on their own due to a symmetric density of states (DOS). In the presence of an external magnetic field, the DOS of the up and down spin states becomes asymmetric separately. A spin filtering material can then be added to detect only one of the two spin states. Previously, we reported our development of an experimental platform for the measurement of thermoelectric effects in nanoscale devices at sub-Kelvin temperatures. Here, we present our measurements of the Seebeck coefficients of superconducting, ferromagnetic, and S-F hybrid nanostructures and our progress towards direct determination of thermoelectric efficiency. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S27.00011: Nonlinear thermoelectric effects in MoGe films Hiroki Arisawa, Yuto Fujimoto, Takashi Kikkawa, Eiji Saitoh Thermoelectric effects refer to the voltage generation from temperature gradients in a solid. Although the linear thermoelectric effects have been used in heat-power generation, the thermoelectric voltage disappears when temperature fluctuates temporarily or spatially without macroscopic temperature gradients, limiting their application. In contrast to the linear thermoelectric effects, nonlinear thermoelectric effects, which have been theoretically predicted, can convert temperature fluctuations into electric power, breaking through the limit. In this talk, we report second-order nonlinear thermoelectric effects in a superconducting MoGe film on a ferrimagnetic insulator Y3Fe5O12. We found that the MoGe film exhibits a voltage proportional to the square of the applied temperature gradient. In the MoGe film, mobile superconducting vortices, which generate a thermoelectric voltage, can sense the different magnetic environment between the top and bottom surfaces. Our theoretical analysis shows that the magnetic asymmetry between the surfaces of the MoGe film is attributable to the nonlinear thermoelectric effects. Our result will offer an operating principle for power generators from temperature fluctuations. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S27.00012: Criss-cross Josephson junction devices with InAs nanowires Tasnum Reza, An-Hsi Chen, Moira Hocevar, Sergey M Frolov Devices based on superconductor-semiconductor nanowire junctions are a building block of superconducting qubits and a platform to discover new physics phenomena, such as Majorana Zero Modes. The quality of these hybrid materials is crucial however the standard method of fabricating junctions by etching can easily damage the nanowires. In-situ superconductor evaporation on crossed nanowire networks can also create nanowire junctions, however it requires a well-developed nanowire growth on a patterned substrate. In this work, we develop a new etch-free technique of fabricating Josephson junction devices based on InAs nanowires. We design these devices by placing one nanowire on top of another in a criss-cross fashion on a gate-tunable semiconductor chip. The top nanowire shadows the bottom one during superconductor evaporation/collimated sputtering which results in a sub-100nm width junction on the bottom nanowire. This could in principle create induced hard gap superconductivity in the nanowire junctions. In this talk we will discuss our progress with fabrication, proof of principle quantum transport data and future work on such devices. |
Thursday, March 9, 2023 10:24AM - 10:36AM |
S27.00013: Cyclic superconducting quantum refrigerators using guided fluxon propagation TATHAGATA KARMAKAR, Etienne Jussiau, Sreenath K Manikandan, Andrew N Jordan We describe quantum refrigerator cycles using magnetic flux vortices in a Type-II superconductor as the cooling agent. We delineate the corresponding thermodynamic cycles for s-wave and d-wave symmetric superconductors. The cooling is achieved by the adiabatic magnetization of flux vortices moving across a magnetic field gradient, driven by an external current source. Additionally, we provide a dynamical description of the heat exchanges with reservoirs and characterize the performance of the refrigerator. Such a refrigerator can be useful in implementing cooling mechanisms in ongoing superconducting circuits and circuit quantum electrodynamical experiments. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S27.00014: Refrigeration Methods using Adiabatic Magnetization on Type-I and High Tc Superconductors Alok Nath Singh We will study solid state refrigeration methods using type-I superconductors and high Tc superconductors. We employ the formation of intermediate state in both types of the superconductors as the source for cooling. Type-I superconductors can act as a working substance on which work is applied through magnetic field to cool down a normal metal substrate. We look to optimize the refrigeration cycles in two different cases. The first case is when the substrate, the working substance and the reservoir are detachable. The second case is when all three are in contact with each other at all times. Our analysis suggests that it is possible to cool down the substrate to around 1 mK starting from 100 mK. A similar method for refrigeration will be studied using the high Tc superconductor, which has the benefit of a higher temperature range for the reservoir. |
Thursday, March 9, 2023 10:48AM - 11:00AM |
S27.00015: Bipolar Thermoelectric Josephson Engine Gaia Germanese The direct conversion of a thermal gradient into an electrical power, known as thermoelectric effect, was considered impossible in pristine superconductors due to the perfect particle-hole symmetry around the Fermi surface. Linear thermoelectric phenomena in superconducting systems were obtained only by explicitly breaking the particle-hole symmetry [Ref. 1-3]. |
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