Bulletin of the American Physical Society
APS March Meeting 2024
Monday–Friday, March 4–8, 2024; Minneapolis & Virtual
Session D16: Emerging Superconductors and Topological Materials |
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Sponsoring Units: DCMP Chair: Yusuke Iguchi, Stanford university Room: M100G |
Monday, March 4, 2024 3:00PM - 3:12PM |
D16.00001: Tuning superconductivity by rare-earth element doping in Bi-based high TC cuprate superconductors Maria Bambrick-Santoyo, Peter van Vlaanderen, Jinming Yang, Tyler L Werner, Ruobin Han, Siqi Wang, Ioan-Augustin Chioar, Jeremy Mao, Yu He Motivated by over three decades of studies on elemental doping of high temperature cuprate superconductors, we explore the superconducting mechanism by studying its enemies. By understanding how superconductivity can be “killed” with elemental substitution, we hope to glean insights into the factors critical to enabling it. We identify cerium and praseodymium as the two elements most effective at suppressing superconductivity in Bi2Sr2CaCu2O8 (Bi-2212) without directly substituting copper, and incorporate them into the crystal lattice at varying concentrations. Making use of angle-resolved photoemission spectroscopy (ARPES) and single-crystal x-ray diffraction, we investigate the electronic and structural properties of the doped and undoped systems, including charge doping, modulations in the superstructure, substitution site of the Ce/Pr atoms, and changes to the low-energy electronic structures. In doing this, we extract factors that negatively impact superconductivity. This knowledge can not only inform future studies exploring ways to mitigate these negative factors, but also provide insight into microscopic engineering principles to boost superconductivity towards higher temperatures. |
Monday, March 4, 2024 3:12PM - 3:24PM |
D16.00002: Superconducting cobalt disilicide thin films for quantum information technolgy Wilson J Yanez Parreno, Teun van Schijndel, Anthony McFadden, Yu Wu, Raymond W Simmonds, Chris Palmstrom In the past few decades, there has been tremendous progress in the field of superconducting quantum information technology. Nevertheless, scalability and decoherence are still major challenges that need to be overcome for these systems to be implemented on a large scale. One way to make progress on the field is by carefully engineering the materials and devices that constitute them. In this context, we report the synthesis of closely lattice matched superconducting cobalt disilicide thin films grown on low loss silicon (111) substrates using molecular beam epitaxy. We characterize the structure of the films using reflection high energy electron diffraction, atomic force microscopy and x-ray diffraction. We then study the superconductivity of the films by performing electrical transport measurements down to 50 mK. Finally, we explore the fabrication of distributed and lumped element resonator circuits and Josephson junctions based on Si fins which can be used in superconducting circuits and merged element transmon applications. |
Monday, March 4, 2024 3:24PM - 3:36PM |
D16.00003: Critical Field Anisotropy and Muon Spin Relaxation Study of Superconducting Dirac-Semimetal CaSb2 Mohamed Oudah, Yipeng Cai, Marta-Villa De Toro Sanchez, Jörn Bannies, Meigan C Aronson, Kenji M Kojima, Douglas A Bonn CaSb2 has been identified as a topological semimetal [1] and a bulk superconductor[2,3], which makes it a great platform for realizing topological superconductivity. We investigate the superconducting upper and lower critical field anisotropy using magnetic susceptibility on single crystals [4], and study the superconducting state using muon spin-relaxation. The temperature dependence of transverse-field relaxation can be fitted with a single-gap model or two-gap model [4], consistent with previous tunnel-diode oscillator measurements. Zero-field relaxation shows little temperature dependence when the muon-spin is parallel to the c∗-axis, while an increase in relaxation appears below 1~K when the muon-spin is parallel to the ab-plane. This may be related to a second superconducting phase appearing at low temperature below the bulk Tc. However, we find no discernible anomaly in μ0Hc1(0) around this temperature as has been seen in other superconductors with secondary superconducting states that appear at lower temperatures. |
Monday, March 4, 2024 3:36PM - 3:48PM |
D16.00004: X-ray and neutron diffuse scattering and Monte Carlo modeling of local structure in the cuprate HgBa2CuO4+δ Zachary W Anderson, Marin Spaić, Nikolaos Biniskos, Biqiong Yu, Jack Zwettler, Yaohua Liu, Feng Ye, Matthew J Krogstad, Raymond Osborn, Damjan Pelc, Martin Greven The cuprates are known as hosts of high-temperature superconductivity and of other correlated electronic phases, but the well-documented inhomogeneity of these materials is generally not considered. It was recently shown that, at a phenomenological level, much of the doping- and temperature-dependence of the seemingly complicated electronic phase diagram can be understood as rooted in a distribution of local environments [1]. Recent advances in X-ray and neutron diffuse scattering techniques have made it possible to determine correlated deviations from the average structure of materials. Here we report on X-ray and neutron diffuse scattering measurements of the structurally simple compound HgBa2CuO4+δ along with pair-distribution-function analysis of the data and reverse Monte Carlo refinement of the local structure. We will discuss the observed deviations from average structure and the implications of these results for the cuprates in general. |
Monday, March 4, 2024 3:48PM - 4:00PM |
D16.00005: Unusual short-range structural fluctuations in La2-xSrxCuO4 and La2-xSrxNiO4 Richard J Spieker, Dayu Zhai, Marin Spaić, Xing He, Issam Khayr, Nina G Bielinski, Matthew J Krogstad, Feng Ye, Raymond Osborn, Damjan Pelc, Martin Greven Understanding the connection between structural and electronic properties in complex oxides is of fundamental importance. Our recent x-ray and neutron scattering measurements of the high-Tc superconductors La2-xSrxCuO4 and Tl2Ba2CuO6+δ revealed unusual scaling behavior of short-range orthorhombic fluctuations across the temperature-doping phase diagram, including for nominally tetragonal compositions [1]. In particular, we observe an exponential dependence of the scattering intensity on absolute (rather than reduced) temperature, analogous to recent findings for the superconducting precursor of cuprates and other oxides [2]. Here we report on efforts to extend these measurements to higher temperatures for La2-xSrxCuO4 and to the isostructural insulating nickelate La2-xSrxNiO4. Our results suggest that structural fluctuations are necessary to understand the electronic properties of these materials, and they point to the pivotal importance of underlying structural inhomogeneity and to a possible connection with Urbach (or Lifshitz) tails previously observed near the optical band edge in various amorphous, disordered, and crystalline materials [3]. |
Monday, March 4, 2024 4:00PM - 4:12PM |
D16.00006: Superconducting properties of the spin Hall candidates Ti3Ir and Ti3Pt Matthew P Smylie, Ramakanta Chapai, Ulrich Welp, Xinglong Chen, Duck Young Chung, Wai-Kwong Kwok, John F Mitchell Materials with A15 structure are emerging as a novel platform for realizing new phenomena resulting from the interplay of superconductivity, band topology and spin dynamics. Here, we present a study of the superconducting properties of the spin Hall candidate Ti3Ir, an A15 compound, and its homolog Ti3Pt. Bulk measurements including electrical resistivity, magnetic susceptibility and specific heat on Ti3Ir show two clear anomalies: a superconducting transition at Tc ~ 4.5 K, and an anomaly at higher temperature T* ~ 90 K. Ti3Pt has a superconducting Tc ~ 0.8 K but does not display an anomaly at temperatures above Tc. We attribute the high temperature transition in Ti3Ir to crystal symmetry breaking resulting in a possible martensitic transition and charge density wave (CDW) formation. Via multiple techniques, we determine a superconducting phase diagram for each material and find large Ginzburg-Landau parameters, identifying both materials as extreme type-II. London penetration depth measurements at 3He temperatures on Ti3Ir are consistent with a full BCS-like superconducting gap. |
Monday, March 4, 2024 4:12PM - 4:24PM |
D16.00007: Low temperature electronic transport properties of ultrathin, single crystal WC and W2C nanoplates Alex Sredenschek, David E Sanchez, Jiayang Wang, Da Zhou, Le Yi, Morteza Kayyalha, Susan B Sinnott, Mauricio Terrones Transition metal carbides (TMCs) have historically been studied in bulk, non-layered morphologies and applied for high hardness, chemical stability, and electrocatalytic activity. This family has received renewed interest with the development of novel top-down and bottom-up approaches to isolate layered (MXenes)1 and ultrathin, non-layered TMCs (UThTMCs).2 While the MXene family has a wide range of applications,3 electronic transport properties can be difficult to probe owing to small domain size. UThTMCs were shown to be isolated as single crystal nanoplates, such as molybdenum2 and tungsten carbide4 which were shown to exhibit quasi-2D electronic states. Following recent works in bottom-up synthesis of UThTMCs,4,5 we isolate WC and W2C using liquid-metal-assisted chemical vapor deposition. We identify crystal phase using a combination of X-ray and electron diffraction. Atomic force microscopy reveals that the thickness of these crystals is below 50 nm. We find that down to 10 mK, WC does not enter a superconducting state. In W2C, we observe a superconducting transition, discuss the temperature dependence of the critical fields, and extract Ginzburg-Landua coherence lengths both in and out-of-plane. |
Monday, March 4, 2024 4:24PM - 4:36PM |
D16.00008: Low-energy charge dynamics of infinite-layer nickelates: evidence for d-wave superconductivity Bing Cheng, Di Cheng, Kyuho Lee, Liang Luo, Zhuoyu Chen, Yonghun Lee, Bai Yang Wang, Martin Mootz, Chuankun Huang, Ilias Perakis, Zhi-Xun Shen, Harold Hwang, JIGANG Wang The discovery of superconductivity in infinite-layer nickelates establishes a new category of unconventional superconductors that shares structural and electronic similarities with cuprates. Despite the exciting advances, the key issues of the superconducting pairing symmetry, gap amplitude, superconducting fluctuation and collective modes remain elusive. In this talk, I will show how we utilize static and ultrafast terahertz spectroscopy to address these outstanding problems. We demonstrate that the equilibrium terahertz conductivity and nonequilibrium terahertz responses of an optimally Sr-doped nickelate film (Tc = 17 K) are in line with the electrodynamics of d-wave superconductivity in the dirty limit. The gap-to-Tc ratio is extracted to be 3.4, which indicates the superconductivity falls in the weak-coupling regime. In addition, we observed significant superconducting fluctuation near Tc. These results highlights a new d-wave system which closely resembles the electron-doped cuprates, expanding the family of unconventional superconductivity in oxides. Finally, we will present evidence for highly damped Higgs mode in infinite-layer nickelates. |
Monday, March 4, 2024 4:36PM - 4:48PM |
D16.00009: Spin susceptibility of nonunitary spin-triplet superconductors Thomas Bernat The description of unconventional superconductors relies on the identification of their pairing symmetry. In centrosymmetric crystals, pairs have either a spin-singlet or spin-triplet wave function. The most general spin triplet phase is nonunitary, and originates from unequal contributions of opposite spins. As a consequence, time-reversal symmetry is broken and the excitation spectrum consists of two non-degenerate bands. Such pairing may occur in chiral superconductors with strong spin-orbit coupling, and is suspected in a number of compounds. The spin susceptibility is an important probe to characterize the symmetry of the order parameter, and can be inferred from Knight shift or polarized neutron scattering measurements. Surprisingly it has not been calculated for nonunitary triplet phases. Our study fills this gap by providing a general formula for the spin susceptibility of nonmagnetic single-band centrosymmetric triplet superconductors with strong spin-orbit coupling. We apply it to group theoretically admissible nonunitary phases of specific crystal symmetries in the presence of strong spin-orbit coupling. We discuss implications for various experimental studies. Our results pave the way for further investigation of nonunitary triplet superconductivity in more complex systems. |
Monday, March 4, 2024 4:48PM - 5:00PM |
D16.00010: Terahertz Higgs Echo Spectroscopy of a Niobium Superconductor Chuankun Huang, Martin Mootz, Liang Luo, Yihua Qiang, Victor Quito, Peter P Orth, Ilias Perakis, JIGANG Wang, Avinash Khatri THz multi-dimensional coherent spectroscopy (MDCS) has been proven to be a powerful tool to study driven quantum systems and discover collective modes in superconductors. Here, we report the observation of robust Higgs echoes in a Niobium superconductor through phase-locked pulse-pair coherent driving using THz-MDCS. The nonlinear quantum excitation pathway of the echo signals demonstrates an unambiguous origin from Higgs mode excitation and separate the Higgs peaks from quasi-particle (QP) ones. We also reveal Higgs-Higgs interactions from the correlative modulation of the superconductor order parameter . Our quantum kinetic simulations capture the spectral-temporal features from experiment results and unravel the role of Higgs-Higgs interactions in the formation of echoes. Our discovery provides a deep insight into the exotic coherence and correlation from superconducting amplitude channels, bringing a new view of manipulating the correlated quantum systems. |
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