Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session S48: Superconductivity: Transport PropertiesLive
|
Hide Abstracts |
Sponsoring Units: DCMP Chair: Timir Datta, Univ of South Carolina |
Thursday, March 18, 2021 11:30AM - 11:42AM Live |
S48.00001: Thermal Hall Conductivity in Cuprates Marie-Eve Boulanger, Gael Grissonnanche, Sven Badoux, Etienne Lefrancois, Anaelle Legros, Adrien Gourgout, Maxime Dion, Cuihuan Wang, Xianhui Chen, Ruixing Liang, Walter N Hardy, Douglas A. Bonn, Louis Taillefer Thermal Hall conductivity (kxy) has been used to characterize the pseudogap phase of hole-doped cuprates [1]. A new and unexpected result was found: the presence of a negative thermal Hall signal appearing in the pseudogap phase, which grows as the sample becomes insulating, being maximal in the Mott insulator La2CuO4. The heat carriers responsible for that large thermal Hall conductivity were shown to be phonons [2]. |
Thursday, March 18, 2021 11:42AM - 11:54AM Live |
S48.00002: Chiral phonons in the pseudogap phase of cuprates Steven Thériault, Gael Grissonnanche, Adrien Gourgout, Marie-Eve Boulanger, Etienne Lefrancois, Francis Laliberte, Amirreza Ataei, Maxime Dion, Sunseng Pyon, Jianshi Zhou, Tomohiro Takayama, Hidenori Takagi, Nicolas Doiron-Leyraud, Louis Taillefer The nature of the pseudogap phase of cuprates remains a major puzzle. In the cuprate Nd-LSCO, a large negative thermal Hall conductivity κxy was seen to appear when the doping p is lowered below the critical doping of the pseudogap phase p* [1]. Its origin is still unknown. Here we show that the thermal Hall conductivity of the Mott insulator La2CuO4 is roughly the same for heat transport parallel and normal to the CuO2 planes, i.e. κzy(T) ≈ κxy(T) [2]. This shows that the Hall response must come from phonons, as they are the only heat carriers that are able to move with the same ease both normal and parallel to the planes. |
Thursday, March 18, 2021 11:54AM - 12:06PM Live |
S48.00003: Linear-in-field magnetoresistance in cuprates Amirreza Ataei, Adrien Gourgout, Francis Laliberte, Sven Badoux, Gael Grissonnanche, siham benhabib, David Vignolles, Jianshi Zhou, Nicolas Doiron-Leyraud, Cyril Proust, Louis Taillefer The normal state of cuprate superconductors near the pseudogap critical point p* has been investigated by various measurements in high magnetic fields [1]. Resistivity shows a T-linear regime near p* whose magnitude appears to be controlled by a scattering rate in the Planckian limit [2]. |
Thursday, March 18, 2021 12:06PM - 12:18PM Live |
S48.00004: Thermal Transport in Superconductors with coexisting Spin Density Wave Order Sourav Sen Choudhury, Anton Vorontsov Thermal conductivity measurements are a very useful probe of superconductivity as it can reveal the gap structure of unconventional superconductors. Here we study thermal transport in a two-dimensional system with coexisting Superconducting (SC) and Spin Density Wave (SDW) orders. We find that the coexistence phase of the dx2-y2 pairing state is fully gapped, whereas new zero energy excitations appear in the case of dxy and s-wave pairing states. These exications are not gapped by the SC order in the coexistence phase. The occurrence of these zero energy excitations is related to the symmetry properties of the pairing states. We compute the electronic thermal conductivity within the framework of Boltzmann kinetic theory, using Born approximation for the impurity scattering collision integral. We describe the influence of the Fermi surface (FS) topology, the competition between the SC and SDW order parameters, the presence or absence of zero energy excitations in the coexistence phase, on the low temperature behaviour of thermal conductivity of the various paring states. We present numerical results that show that the heat transport signatures of these paring states are quite distinct. |
Thursday, March 18, 2021 12:18PM - 12:30PM Live |
S48.00005: Thermoelectric Effects in Superconductor-Ferromagnetic Heterostructures Kirsten Blagg, Portia Allen, Meenakshi Singh Superconductor-ferromagnetic (SF) structures have been shown to host a variety of interesting physics. In particular, thermoelectric effects have recently excited a wealth of research. While conventional superconductors are known to be poor thermoelectric materials, the combined effects of spin splitting and spin filtering creates an asymmetry in the density of states and generates large thermoelectric effects. These SF systems have been predicted to have a thermoelectric figure of merit (zT) of 1.8, far exceeding any other thermoelectric materials at cryogenic temperatures. Here, we directly measure the Seebeck coefficient (△V/△T) of an Al-Ni junction below 1 K. To accurately measure and generate a temperature gradient, we utilize focused-ion beam deposited platinum (FIB Pt) as local nanoscale resistive thermometers and an FIB Pt on-chip joule heater. We measure a local maximum in the Seebeck coefficient with respect to both temperature and magnetic field. These features are attributed to the competing effects of: 1) increased quasiparticle density and peak broadening with increasing temperatures and 2) increased Zeeman splitting and spin-scattering effects due to an increasing magnetic field. |
Thursday, March 18, 2021 12:30PM - 12:42PM Live |
S48.00006: Spin Valve Effect in all-oxide Superconductor/Ferromagnet Junctions Aurélien LAGARRIGUE, Salvatore Mesoraca, David Sanchez, Anke Sander, Javier Briatico, Juan Trastoy, Jacobo Santamaria, Javier E Villegas Due to their antagonistic properties, the interaction between ferromagnets and superconductors yields interesting behaviours such as the so-called superconducting spin valve effect. This is observed in junctions made of two ferromagnetic layers sandwiching a superconductor. The term spin-valve denotes the electrical resistance change observed upon switching the relative magnetizations in the ferromagnetic layers, from parallel to antiparallel alignment, by the application of magnetic field pulses. Here we demonstrate spin-valve effects in vertical junctions made of the d-wave superconductor YBa2Cu3O7 and a half-metal La0.7Ca0.3MnO3. Below the superconducting critical temperature, the junctions show a hysteretic magnetoresistance whose sign changes depending on the temperature and the injected current. These effects are discussed in terms of triplet Cooper pairs flow when the two ferromagnets are aligned. |
Thursday, March 18, 2021 12:42PM - 12:54PM Live |
S48.00007: Giant surface Edelstein effect in d-wave superconductors Yuhei Ikeda, Youichi Yanase Edelstein effect is useful for electric control of magnetic moment. However, Joule heating created by a dissipative current is harmful for its practical applications. We investigate two-dimensional noncentrosymmetric superconductors (NCSs) with either s-wave or d-wave symmetry, and demonstrate that a surface Edelstein effect is significantly enhanced in d-wave NCSs. In this talk, I will discuss the origin of the enhancement and show that this is attributed to surface Majorana states characteristic of gapless spin-singlet non-centrosymmetric superconductors. In the view of superconducting spintronics, this result would give a route to magnetic domain switching by dissipationless supercurrent. |
Thursday, March 18, 2021 12:54PM - 1:06PM Live |
S48.00008: High magnetic field compatible nanowire hybrids (part I): Conductance spectroscopy Grzegorz Mazur, Nick van Loo, Marina Quintero-Peréz, Jiyin Wang, Peter Vinke, Robin Dekker, Francesco Borsoi, Mariusz Andrzejczuk, Ghada Badawy, Sasa Gazibegovic, Erik P. A. M. Bakkers, Sebastian Heedt, Leo Kouwenhoven Semiconductor nanowires coupled to superconductors are promising candidates for realizing topological superconductivity in solid state systems. The first generation of nanowire-superconductor devices utilized Nb based alloys with large superconducting gaps providing opportunity to operate at high magnetic fields and temperatures. Due to the soft gap, Nb-based superconductors were subsituted with Aluminum. As a result, hard gap and parity conserving transport are commonly observed in III-V/Al hybrids. A limiting factor for Al based systems is a rather narrow parameter space defined by small superconducting gap and resulting modest magnetic field resilience. I will discuss opportunities for increasing field compatibility of InSb/Al hybrids by lifting the Pauli limit within the superconducting segment. Furthermore, I will present how such an approach can be utilized for reaching critical field values doubling the values reported so far. Finally, I will present results of conductance spectroscopy of InSb/Al nanowire devices taken at high magnetic fields. |
Thursday, March 18, 2021 1:06PM - 1:18PM Live |
S48.00009: High magnetic field compatible nanowire hybrids (part II): exploring bulk induced superconductivity Nick van Loo, Grzegorz Mazur, Jiyin Wang, Robin Dekker, Ghada Badawy, Sasa Gazibegovic, Erik P. A. M. Bakkers, Sebastian Heedt, Leo Kouwenhoven Semiconductor nanowires coupled to superconductors are promising candidates for realizing topological superconductivity in solid state systems. We have developed a technique which increases the field compatibility of InSb/Al hybrids dramatically, of which the basic characterization is discussed in the previous talk (Conductance spectroscopy of high magnetic field compatible nanowire hybrids (part I)). In this work, we go beyond standard density-of-states spectroscopy. In a 3-terminal geometry, we explore the induced superconductivity in the bulk of these hybrids by means of non-local conductance measurements. At the two ends of the superconducting section, we use local spectroscopy to probe the density of states in the nanowire. At the same time, we measure the non-local signal and track the evolution of the induced gap in the bulk of the nanowire as a function of magnetic field and gate voltage. Crucially, the combination of high-mobility semiconducting wires and a field-resilient superconductor allows us to operate these hybrids at magnetic fields which are uniquely accessible in our system. |
Thursday, March 18, 2021 1:18PM - 1:30PM Live |
S48.00010: Thermoelectric detection of Andreev states in unconventional superconductors Tony Savander, Shun Tamura, Christian Flindt, Yukio Tanaka, Pablo Burset We theoretically describe a thermoelectric effect that is entirely due to Andreev processes involving the formation of Cooper pairs through the coupling of electrons and holes. The Andreev thermoelectric effect can occur in ballistic ferromagnet-superconductor junctions with a dominant superconducting proximity effect on the ferromagnet, and it is very sensitive to surface states emerging in unconventional superconductors. We consider hybrid junctions in two and three dimensions to demonstrate that the thermoelectric current is always reversed in the presence of low-energy Andreev bound states at the superconductor surface. A microscopic analysis of the proximity-induced pairing reveals that the thermoelectric effect only arises if even and odd-frequency Cooper pairs coexist in mixed singlet and triplet states. Our results are an example of the richness of emergent phenomena in systems that combine magnetism and superconductivity, and they open a pathway for exploring exotic surface states in unconventional superconductors. |
Thursday, March 18, 2021 1:30PM - 1:42PM Live |
S48.00011: DC Hall measurements in the strongly correlated Hubbard model Wen Wang, Jixun Ding, Brian John Moritz, Edwin Huang, Thomas Devereaux We investigate the DC Hall conductivity, an indicator of charge carrier properties, of the single-band Hubbard model in the zero field limit[1] using determinant quantum Monte Carlo (DQMC). Utilizing an effective expansion to lowest order, we observe a change of sign in the Hall coefficient as a function of temperature and interaction strength, which may signal a change in the topology of the Fermi surface. We relate the Hall coefficient to the frequency dependent resistivity, also obtained from DQMC following analytic continuation, to reveal the properties of charge carriers within the strange metal phase of the Hubbard model. |
Thursday, March 18, 2021 1:42PM - 1:54PM Live |
S48.00012: Electrical and Thermal Transport in Antiferromagnet-Superconductor Junctions Martin Jakobsen, Arne Brataas, Paramita Dutta, Kristian Naess, Alireza Qaiumzadeh We demonstrate that antiferromagnet-superconductor (AF-S) junctions show qualitatively different transport properties than normal metal-superconductor (N-S) and ferromagnet-superconductor (F-S) junctions. We attribute these transport features to the presence of two new scattering processes in AF-S junctions, i.e., specular reflection of holes and retroreflection of electrons. Using the Blonder-Tinkham-Klapwijk formalism, we find that the electrical and thermal conductance depend nontrivially on antiferromagnetic exchange strength, voltage, and temperature bias. Furthermore, we show that the interplay between the Néel vector direction and the interfacial Rashba spin-orbit coupling leads to a large anisotropic magnetoresistance. The unusual transport properties make AF-S interfaces unique among the traditional condensed-matter-system-based superconducting junctions. |
Thursday, March 18, 2021 1:54PM - 2:06PM Live |
S48.00013: Retention of the high-pressure-induced metastable superconducting phases in Bi Trevor Bontke, Liangzi Deng, Rabin Dahal, Zhen Wu, Ching W Chu To investigate the potential industrial application of high pressure superconductivity, the effect of pressure quenching at liquid nitrogen temperature was studied on the non-superconducting single crystal bismuth (Bi) up to 12 GPa, where three superconducting phases are pressure induced. They are the monoclinic phase (Bi-II), tetragonal host-guest phase (Bi-III), and bcc phase (Bi-V), progressively with increase of pressure. Superconducting phases with Tc up to ~ 7 K were retained upon pressure quenching, with Bi-III being the most robust state. The retained superconducting phase stability of Bi-III was tested with thermal cycles. Our results indicate that phase may be related to post-quench residual pressure. The results of pressure quenching experiments demonstrated that metastable phases can be exploited to retain higher Tcs at ambient pressure. Furthermore, this technique also shows potential to quickly map out different metastable phases. |
Thursday, March 18, 2021 2:06PM - 2:18PM Live |
S48.00014: Electron-phonon and electron-electron interactions in electron doped aromatic carbon materials viewed from electrical transport Katsumi Tanigaki, Yuki Matsuda, Satoshi Heguri A Mott physics on unconventional superconductors, such as cuprates, Fe pnictides, and organic conductors is now claimed for electron-doped aromatic hydrocarbon such as antracene, tetracene, pentacene, and expanded C60 as well as even in graphene. Although, relatively high Tc in superconductivity was once claimed for simple aromatic hydrocarbons with electron carrier filling into their bands by alkali-metal insertion, the real electronics states have not yet been understood so far. This is partly because important scientific discussions have been made based on only limited magnetic and optical probes. The Fermi surface of A3C60 (A=alkali metals: K, Rb, Cs) superconductors with expanded cell (Vcell(C603-)) provides an intriguing research platform for both e-e and e-ph interactions. However, being different from other unconventional superconductors, electrical transport measurements had been very difficult in expanded A3C60. Here, we give experimental results that accurate electrical resistivity can be achieved for a variety A3C60 with expanded Vcell(C603-) near the Mott boundary and other hydrocarbons under various temperature (T) and pressure (P). |
Thursday, March 18, 2021 2:18PM - 2:30PM Live |
S48.00015: The effect of the pseudogap on thermomagnetic transport in cuprates Rufus Boyack, Zhiqiang Wang, Qijin Chen, Kathryn Levin Recent interest in the cuprate thermal Hall coefficient and longstanding interest in the Wiedemann-Franz ratio emphasize the importance of systematically understanding the thermomagnetic coefficients of the pseudogap phase. Here we present a strong-pairing correlation theory for the pseudogap phase in which both bosonic (or preformed pairs) and gapped fermionic excitations are present. This approach is different from standard fluctuation schemes as it includes pseudogap effects in the general thermomagnetic response. Our formulae are additionally validated by an alternative theoretical formulation of thermomagnetic transport which, instead of the Luttinger gravitational potential, introduces a more physical Leggett-Caldeira particle bath. One goal of this work is to evaluate the Wiedemann-Franz ratio associated with the charge carrier contribution for both the longitudinal and transverse transport at general temperatures. This enables us to discuss the |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700