Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session B61: Superconductivity: Proximity & AndreevRecordings Available
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Sponsoring Units: DCMP Chair: Sanu Mishra, Los alamos National Lab Room: Hyatt Regency Hotel -Field |
Monday, March 14, 2022 11:30AM - 11:42AM |
B61.00001: Scanning SQUID Imaging of Diamagnetism in Proximity Coupled Niobium Nano-Island Arrays on Gold Irene P Zhang, Logan Bishop-Van Horn, Emily N Waite, Tom Lippman, Malcolm Durkin, Nadya Mason, Kathryn Moler, Ilya Sochnikov The effects of disorder can play an important role in the superconductivity of two dimensional materials. Understanding disorder in 2D superconductors can help elucidate the nature of a variety of quantum critical transitions, including the superconductor-insulator transition. Here we present studies of proximity coupled niobium island arrays on gold with engineered disorder that can serve as model systems for disordered 2D superconductors. Local susceptibility measurements via Scanning SQUID Microscopy (SSM) show that the local diamagnetic response of the arrays is inhomogeneous and can be tuned by changing the landscape of island positions. In contrast to previous transport studies that showed that ordered proximity-coupled superconducting island arrays can be well-described as a single Josephson junction, Josephson simulations suggest that the superconducting response of our disordered arrays cannot be fully explained by a junction array model. Our work suggests new directions for studying a wider parameter space of disorder in 2D superconducting materials and motivates future experiments with more exotic materials. |
Monday, March 14, 2022 11:42AM - 11:54AM |
B61.00002: Hybrid superconductor-semiconductor double nanowire devices Kasper Grove-Rasmussen Presenting author: Kasper Grove-Rasmussen, Co-authors: See references below. |
Monday, March 14, 2022 11:54AM - 12:06PM |
B61.00003: Correlating parity transitions with zero-bias peaks in hybrid semiconducting-superconducting nanowires. Maksim Borovkov, Marco Valentini, Pablo San-Jose, Elsa Prada, Fernando Peñaranda, Sara Martí-Sánchez, Marc Botifoll, Jordi Arbiol, Peter Krogstrup, Ramon Aguado, Georgios Katsaros Semiconducting nanowires covered by superconducting shells have been intensively investigated for almost a decade due to their potential to host non-abelian topological excitations - Majorana zero modes (MZMs) [1, 2, 3, 4]. To date, two methods have been primarily used for their identification: tunneling and Coulomb spectroscopy. Here we present an experimental protocol that allows to perform both types of spectroscopy measurements on the same device. We demonstrate that despite the absence of zero-bias peaks in tunneling spectroscopy, 2e-1e parity transitions in island experiments can be observed. Our results emphasize the need of combined measurements in order to unambiguously demonstrate the existence of MZMs. |
Monday, March 14, 2022 12:06PM - 12:18PM |
B61.00004: Evidence for anisotropic spin-triplet Andreev reflection at the 2D van der Waals ferromagnet/superconductor interface Ranran Cai, YUNYAN YAO, Peng Lv, Yang Ma, Wenyu Xing, Boning Li, Yuan Ji, Huibin Zhou, Chenghao Shen, Shuang Jia, X.C. Xie, Igor Zutic, Qing-Feng Sun, Wei Han Fundamental symmetry breaking and relativistic spin–orbit coupling give rise to fascinating phenomena in quantum materials. Of particular interest are the interfaces between ferromagnets and common s-wave superconductors, where the emergent spin-orbit fields support elusive spin-triplet superconductivity, crucial for superconducting spintronics and topologically-protected Majorana bound states. Here, we report the observation of large magnetoresistances at the interface between a quasi-two-dimensional van der Waals ferromagnet Fe0.29TaS2 and a conventional s-wave superconductor NbN, which provides the possible experimental evidence for the spin triplet Andreev reflection and induced spin-triplet superconductivity at ferromagnet/superconductor interface arising from Rashba spin-orbit coupling. The temperature, voltage, and interfacial barrier dependences of the magnetoresistance further support the induced spin-triplet superconductivity and spin-triplet Andreev reflection. This discovery, together with the impressive advances in two-dimensional van der Waals ferromagnets, opens an important opportunity to design and probe superconducting interfaces with exotic properties. |
Monday, March 14, 2022 12:18PM - 12:30PM |
B61.00005: Transition from 3-dimensional to 2-dimensional Ising superconductivity in few-layer NbSe2 by proximity effect from van der Waals heterostacking Prakiran Baidya, Divya Sahani, Hemanta Kumar Kundu, Simrandeep Kaur, Priya Tiwari, Vivas Bagwe, John Jesudasan, Awadhesh Narayan, Pratap Raychaudhuri, Aveek Bid The coexistence of superconductivity and spin-orbit coupling in an Ising superconductor has garnered attention in recent times due to its prospect of having topologically non-trivial phases. In this work, we report the observation of Ising superconductivity in a bulk NbSe2 stacked over a monolayer MoS2 which in contrast to earlier reports has advantage in terms of yield, stability, and flexibility for complex device structure. Through systematic and comparative magnetotransport measurement we confirmed the existence of 2D Ising superconductivity in the heterostructure with 3D behavior of the pristine NbSe2. The 2D nature of the superconductivity in the stack was further probed through resistance fluctuation spectroscopy establishing universal BKT type behavior. Moreover, we studied the vortex dynamics of the system in perpendicular magnetic field which shows the influence of monolayer MoS2 in transport characteristics of the heterostructure. |
Monday, March 14, 2022 12:30PM - 12:42PM |
B61.00006: Induced superconductivity in semiconducting 2D Te Chang Niu, Mingyi Wang, Zhuocheng Zhang, Gang Qiu, Yixiu Wang, Wenzhuo Wu, Peide (Peter) Ye Superconductor and semiconductor hybrid devices emerge as an important system for the research on exotic physics phenomena and the realization of quantum computing. Superconductor to semiconductor interface is essential for the performance of a hybrid device. Here, we report a new route to induce superconductivity into semiconductors by “intimate contact” in Tellurium (Te) based material system. Te is a narrow bandgap semiconductor with a unique chiral crystal structure. The 2D Te single crystal is synthesized using a solution process. After the deposition of Pd electrodes, PdTe superconductor is formed. Supercurrent with gate tunability is observed in PdTe-Te-PdTe hybrid devices which can be used as functional superconducting transistors. Our work provides an alternative way to induce superconductivity into non-superconducting materials. |
Monday, March 14, 2022 12:42PM - 12:54PM |
B61.00007: Microwave response of an Andreev level Pavel Kurilovich, Valla Fatemi, Vladislav Kurilovich, Max Hays, Nicholas E Frattini, Daniel Bouman, Thomas Connolly, Spencer Diamond, Peter Krogstrup, Jesper Nygard, Attila Geresdi, Leonid Glazman, Michel H Devoret We measured the microwave response of an Andreev level formed in a semiconducting nanowire quantum dot connecting two superconducting leads using a circuit quantum electrodynamics probe. This probe gave us unprecedented access to the physics of Andreev levels by making it possible to separately measure the response of different many-body configurations of the system. Comparing these responses, we observed the violation of the particle-hole symmetry that points to an appreciable Coulomb interaction in the dot. We also found that the energy-phase relation of a state with a single electron at the dot had a strong π-shifted phase dependence, which can be attributed to contribution of the continuum states to the supercurrent. Our results are in a good agreement with a minimal theoretical model. |
Monday, March 14, 2022 12:54PM - 1:06PM |
B61.00008: Superconducting proximity effect in topological kagome antiferromagent Mn3Sn Tilak R Thapaliya, Sebastian H Parra, James M Kikkawa, Sunxiang Huang Topological superconductivity (TSC) with triplet pairing is of intense interests for topological quantum computing and superconducting spintronics. One route to the realization of TSC is to explore novel proximal superconductivity with real space or momentum space spin textures. Topological kagome antiferromagnet Mn3Sn is a promising contender because of its exotic topological band structures and rich real space non-collinear spin textures. In this work, we report the prominent superconducting proximity effect in Mn3Sn/Nb bilayer films. In comparison with single Nb control samples, we found steplike superconducting transitions, distinct dependence of the transition temperatures on Nb thickness, increases of coherence length, and signs of violation of Pauli paramagnetic limit, suggesting potential proximity-induced triplet pairing in the bilayer films. |
Monday, March 14, 2022 1:06PM - 1:18PM |
B61.00009: Transport Studies of Graphene/Hi-Tc Superconductor Junctions Sharadh Jois, Genda Gu, Qiang Li, Ji Ung Lee Superconductor-graphene-superconductor (S-Gr-S) junctions have been well studied with low-temperature superconductors showing evidence of supercurrent and different Andreev reflection scenarios. We present the results of DC transport in an S-Gr-S junction made with a high-temperature superconductor, Bi2Sr2Ca1Cu2Ox (BSCCO), by mechanically cracking it and stacking it on exfoliated graphene in an inert environment. Due to the large superconducting gap and high upper critical field of BSCCO, we can study the properties of graphene/BSCCO interface over a wide range of parameters, including temperature, bias, doping, and magnetic field, over a robust set of values. We provide evidence of the Dirac nature of graphene at the superconducting junction. The properties of Andreev reflection can be clearly distinguished from the normal carrier transport, which is dominated by the transport properties of graphene. |
Monday, March 14, 2022 1:18PM - 1:30PM |
B61.00010: Statistical detection of Josephson, Andreev, and single quasiparticle currents in scanning tunneling microscopy Wonhee Ko, Eugene F Dumitrescu, Jose Lado, Petro Maksymovych The tunnel junction between superconductors is the heart of many modern quantum information devices, such as superconducting qubits realized from quantum resonators with Josephson junctions. However, several tunneling mechanisms occur simultaneously in the superconducting tunnel junction, and thermal broadening further mixes them to obscure the identification of the tunneling mechanism. Here, we present a method to identify distinct tunneling modes in a tunable superconducting tunnel junction composed of a superconducting tip and sample in a scanning tunneling microscope (STM) [1]. As a testbed of the method, we implemented Pb coated tip to STM and made a tunnel junction with Pb single crystal. Combining the measurement of the relative decay constant of the tunneling current extracted from I-V-z spectroscopy, we identified the crossover of tunneling modes between single quasiparticle tunneling, multiple Andreev reflection, and Josephson tunneling with respect to the bias voltage. The measurement was complemented by the statistical analysis over the atomic disorder in the sample surface, where the distribution of relative decay constant displayed the transition of tunneling mechanism without any presumed physical model. Our method enables one to determine the particular tunneling regime independently of the spectral shapes, and to reveal the intrinsic modulation of Andreev reflection and Josephson current that is crucial for quantum device application of superconductors. |
Monday, March 14, 2022 1:30PM - 1:42PM |
B61.00011: Coexistence of Antiferromagnetism and Superconductivity in Mn ultra-thin films on Nb(110) Roberto Lo Conte, Maciej Bazarnik, Krisztián Palotás, Levente Rózsa, László Szunyogh, André Kubetzka, Kirsten von Bergmann, Roland M Wiesendanger In the last decade, pioneering work has been carried out concerning the study of magnet/superconductor hybrid systems [1,2], due to their potential in hosting topological superconductivity. A recent investigation of Mn adatoms and atomic chains on top of a Nb(110) substrate has shown the emergence of in-gap Yu-Shiba-Rusinov (YSR) states and bands as well as the emergence of p-wave superconductivity [3] and interacting Majorana modes [4], strongly motivating the investigation of Mn films on Nb(110). |
Monday, March 14, 2022 1:42PM - 1:54PM |
B61.00012: Enhancement of the Chiral Andreev Edge State Interference Signals Jordan McCourt We study the interference effects of chiral Andreev edge states (CAES) formed along the |
Monday, March 14, 2022 1:54PM - 2:06PM |
B61.00013: Microwave Sensing of Andreev Bound States in a Gate-Defined Superconducting Quantum Point Contact Malcolm R Connolly, Vivek Chidambaram, Anders Kringh?j, Lucas Casparis, Ferdinand Kuemmeth, Tiantian Wang, Candice Thomas, Sergei Gronin, Geoffrey C Gardner, Michael J Manfra, Karl D Petersson Andreev bound states (ABSs) are coherent superpositions of electrons and holes bound at a junction between two superconductors. Hybrid superconductor-semiconductor junctions allow exquisite control over the number and energy of ABSs using capacitively-coupled gate electrodes. Here we use circuit quantum electrodynamics (cQED) to monitor ABSs in a quantum point contact defined by surface gates over a proximitized two-dimensional electron gas. We infer the ABS structure by comparing a microphysical model of the junction to fits of the cavity frequency as a function of phase difference and gate voltage. Close to pinch-off, we identify features consistent with the presence of a single ABS and describe the Andreev-cavity interaction using a dispersive Jaynes-Cummings model. By fitting the weak Andreev-cavity coupling, we extract ~GHz decoherence consistent with charge noise and the transmission dispersion associated with a single localized state. |
Monday, March 14, 2022 2:06PM - 2:18PM |
B61.00014: DoubleFu-teleportationandanomalousCoulombblockadeinamixedAndreev-Majoranasuperconductingisland Yiru Hao, Donghao Liu, Gu Zhang, Dong E. Liu We study the temperature dependence of Coulomb Blockade peak conductance based on the unilateral coupled four quasi-Majoranas system in trivial phase. This non-local transport system is equivalent to an Andreev bound state (ABS) on the left side of the nanowire and a Majorana bound state (MBS) on the right side. In the low-temperature regime, we discover a coherent double Fu-teleportation (FT), where any independent tunneling process always involve two coherent FTs, and we also obtain a T2 conductance behavior. In the high-temperature regime, using the familiar rate equation method, we find that the conductance is proportional to the reciprocal of the temperature. The non-monotonic temperature-dependent characteristic can be distinguished from the traditional Coulomb block case. Finally, we study the 1e and 2e crossover regimes and find the unique double crossover points, this property can help us implement the detection of our proposed model in the experiment. |
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