Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session F31: Novel Superconductors |
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Sponsoring Units: DCMP Chair: Christian Urban, University of California San Diego Room: LACC 407 |
Tuesday, March 6, 2018 11:15AM - 11:27AM |
F31.00001: Superconductivity in new complex intermetallics Robert Cava, Elizabeth Carnicom, Weiwei Xie, Karoline Stolze, Tomasz Klimczuk In this talk I will breifly describe our recent results on the discovery of superconductivity at temperatures between 2 and 8 K in several previously unreported ternary compounds based on Ta. One of the new materials, based on Ta and a late transition metal, is a noncentrosymmetric chiral superconductor with a HC2(0) that appears to exceed the Pauli limit. If time permits I will also describe our results on a new high entropy alloy superconductor. We have collaborated with many others to complete this work. |
Tuesday, March 6, 2018 11:27AM - 11:39AM |
F31.00002: Algorithms for Rational Design of Oxide High-Tc Superconductors without Copper Onyedinachi Ironkwe The design and search for novel high-Tc superconductors is one of the major challenges of condensed matter Physics. Though serendipity and "enlightened empirical methods" have been key discovery strategies, we have developed a novel powerful rational design algorithm-based framework called MSCD (Material Specific Characterization Dataset), defined in APS March Meeting (2015 APS Abstract S25.00011). Again, in 2016 APS March Meeting, we used MSCD to design YBa2Cu3O7-Like high-Tc superconductors(2016 APS Abstract F8.005). Now we have expanded the design algorithms to include all families of oxide superconductors represented as MnOn and MnOn+1, where M = cations and O = oxide anion and n =1, 2. ...20. Here, we present these MSCD algorithms and examples of material specific designs of families of potential high-Tc oxide superconductors without copper, and their estimated transition temperatures,Tcs. |
Tuesday, March 6, 2018 11:39AM - 11:51AM |
F31.00003: Natural Superconductivity Observed in Meteorites Above 5 K James Wampler, Mark Thiemens, Ivan Schuller Previous studies have shown that meteorites can contain unusual natural phases, such as quasicrystals, that have otherwise been found only in synthetic samples [1]. Because of this, meteorites are good candidates to search for natural superconductivity, which has only been found in Covellite [2]. Because natural samples are inhomogeneous and superconducting phases can be very small, we used Magnetic Field Modulated Microwave Spectroscopy (MFMMS), which can detect 10-12 cc of superconducting material, three orders of magnitude better than Vibrating Sample Magnetometry (VSM). We measured a series of meteorites, surveying representative samples from most major categories of meteorites. In two of the meteorites, we discovered superconducting phases above 5 K using MFMMS, and verified this using VSM. We characterized these phases using Energy-dispersive X-ray spectroscopy and Inductively Coupled Plasma Mass Spectroscopy. To our knowledge, these samples are the first identification of extraterrestrial superconducting phases. They are particularly significant because these materials could be superconducting in extraterrestrial environments. |
Tuesday, March 6, 2018 11:51AM - 12:03PM |
F31.00004: Superconductivity in Pt-doped ScPdBi single crystals Om Prakash, Mason Klemm, Meigan Aronson ScPdBi and ScPtBi are non-centrosymmetric isostructural half-heusler semimetals with different topological character as determined by the band inversion parameter, Δ = Γ8 − Γ6, where Γ6 and Γ8 have s- and p-like electronic characters, respectively. Electronic structure calculations show that ScPdBi is very close to band inversion, with △ = −0.7eV. Nei- ther compound is superconducting above 0.08 K. Substitution of Pt on the Pd-site in ScPdBi is expected to enhance spin-orbit coupling (SOC) and induce band inversion, but remarkably it also induces superconductivity. Neither ScPdBi or ScPtBi is superconducting above .08K, but a superconducting transition below 1.2K with an upper critical field of HC2(0) ≈ 1.6T is observed in electrical resistivity measurements carried out on a single crystal of ScPtxPd1−xBi (x=0.06). Magneto-transport measurements above 1.2K are well fitted to weak anti-localization expressions, indicating that the superconductivity emerges in a two-dimensional conductor. In agreement, no indication of bulk superconductivity is found in specific heat measurements and no Meissner effect is observed. The linear temperature dependence of the upper critical field HC2(T) suggesting unconventional superconductivity. |
Tuesday, March 6, 2018 12:03PM - 12:15PM |
F31.00005: Superconductivity and structural phase transition in BaBi3 under pressure Raquel Ribeiro, Li Xiang, Udhara Kaluarachchi, Manh Cuong Nguyen, Cai-Zhuang Wang, Kai-Ming Ho, Paul Canfield, Sergey Budko Inspired by recent investigations of superconductivity in single crystal BaBi3 [1] we performed a comprehensive pressure study of low field magnetization and electrical resistivity in zero and applied field in single crystals of this compound, combined with first principles calculations. The results suggest that BaBi3 undergoes a pressure-induced structural transition, possibly from a lower pressure (below 1 GPa) tetragonal phase to a higher pressure cubic phase, with the latter being a host for superconductivity with higher Tc. |
Tuesday, March 6, 2018 12:15PM - 12:27PM |
F31.00006: Multi-gap superconductivity in the ternary compound SrPt10P4 with complex new structure Bing Lv, Ben Jawdat, Zheng Wu, Sheng Li, Paul C. W. Chu We report superconductivity at 1.4 K in the new ternary compound SrPt10P4 with a complex new structure. The compound crystallizes in a monoclinic space-group C2/c (#15) with lattice parameters a= 22.9151(9)Å, b= 13.1664(5)Å, c=13.4131(5) Å, and β= 90.0270(5)°. Bulk superconductivity in the sample has been clearly demonstrated through resistivity, ac susceptibility, and heat capacity measurements. Detail specific heat analysis suggests rather weak electron-phonon coupling (ΔCel/ γnTc ~1.02) and multiple gap feature in this compound. High pressure measurements have shown that the superconducting Tc is systematically suppressed upon application of pressure, with a dTc/dP coefficient of -0.016 K/GPa. |
Tuesday, March 6, 2018 12:27PM - 12:39PM |
F31.00007: Antiferromagnetism and Transport Properties of a New Quasi-one-dimensional Material KMn6Bi5 with Unique Mn-cluster Columns Jinke Bao, Zhang-Tu Tang, Duck Young Chung, Guang-Han Cao, Mercouri Kanatzidis Quasi-one-dimensional material consists of one-dimensional structural units which are weakly coupled with each other to form a three-dimensional structure. This structural feature may host interesting states including charge-density-wave and spin-density-wave orders. Recently we have discovered a new quasi-one-dimensional material KMn6Bi5 with unique Mn-cluster columns. It is crystallized in a monoclinic crystal structure and consists of [Mn6Bi5]− columns which are charge-balanced by K. Resistivity, specific heat and magnetization measurements support that it has an antiferromagnetic order at ~ 75 K with short-range spin correlations above the ordering temperature. Resistivity perpendicular to the columns exhibits an incoherent-to-coherent crossover at ~ 40 K, indicating a quasi-one-dimensional electronic property. Detailed structural and transport properties of this compound will be presented in this talk. Our search for emerging superconductivity in this compound by suppressing antiferromagnetism through chemical doping will also be presented. |
Tuesday, March 6, 2018 12:39PM - 12:51PM |
F31.00008: Understanding superconductivity in K2Cr3As3 Keith Taddei, Qiang Zheng, Athena Sefat, Clarina Dela Cruz The discovery of superconductivity in quasi-one-dimensional K2Cr3As3 has opened new avenues to study the arrival of superconductivity from strongly correlated electronic behavior. With a non-centrosymetric structural motif of CrAs double walled tubes built of layered truncated Sierpinski triangles with interior Cr atoms and exterior As atoms, this material is a playground of possible exotic states ranging from Luttinger Liquids to Fulde-Feerel-Larkin-Ovchinnikov vortex lattices. Furthermore, early density functional theory calculations have predicted myriad magnetic ground states, including a ferromagnetic instability which together with the results of transport and local probe measurements have been taken to suggest a possible spin-triplet superconducting state. Yet despite these exciting possibilities, few reports have measured directly any exotic state and the nature of the superconducting state and the relevant fluctuations out of which it arises remains unknown. In this presentation we report on neutron scattering work which helps elucidate the relevant orders in this system. |
Tuesday, March 6, 2018 12:51PM - 1:03PM |
F31.00009: Evidence of existence of line nodes in superconducting gap in K2Cr3As3 from specific heat masurements Jianlin Luo We present low temperature specific heat measurements of the quasi-one-dimensional superconductor K2Cr3As3 in magnetic fields up to 9T. A sharp specific-heat jump around TC is observed, which is much larger than BCS prediction, indicating that this superconductor is in the strong-coupling regime. After subtracting the phonon and the Schottky contribution from the total specific heat, the obtained electronic specific heat at low temperatures is proportional to T2,and the field-dependent electronic specific heat is proportional to H0.5. These results indicate that line nodes are present in the superconducting gap function of K2Cr3As3. |
Tuesday, March 6, 2018 1:03PM - 1:15PM |
F31.00010: Quasilinear quantum magnetoresistance and field-temperature scaling in pressure-induced nonsymmorphic superconductor CrAs Swee Kuan Goh, Niu Qun, Wing Chi Yu, King Yau Yip, Zi Lim, H. Kotegawa, E Matsuoka, H. Sugawara, Hideki Tou, Youichi Yanase The strongly correlated helimagnet CrAs undergoes a quantum phase transition to a nonmagnetic superconductor under pressure [1,2]. We have measured the transverse magnetoresistance of CrAs under pressure [3]. In the pressure range close to where the superconducting transition temperature is maximised, our low-temperature magnetoresistance exhibits a striking non-saturating, quasilinear magnetic field dependence up to 14 T. Our bandstructure calculations reveal a subtle band crossing near the Y-point of the Brillouin zone, which is protected by the nonsymmorphic crystal symmetry. In this presentation, I will show that the quasilinear magnetoresistance arises from an intricate interplay between the nontrivial band crossing and strong magnetic fluctuations. I will also discuss a field-temperature scaling of our data using a recently developed model [4]. Comparisons with the isostructural compound CrP will be made. |
Tuesday, March 6, 2018 1:15PM - 1:27PM |
F31.00011: Noncentrosymmetric Superconductor BeAu Alfred Amon, Eteri Svanidze, Raul Cardoso, Helge Rosner, Murray Wilson, Matej Bobnar, Walter Schnelle, Jeffrey Lynn, Graeme Luke, Andreas Leithe-Jasper, Yuri Grin Noncentrosymmetric superconductors have attracted tremendous research interest due to the |
Tuesday, March 6, 2018 1:27PM - 1:39PM |
F31.00012: Superconductivity in the weakly correlated non-centrosymmetric compounds ThTSi (T = Co, Ni, Ir, Pt) Shanta Saha, Limin Wang, Johnpierre Paglione The discovery of unconventional superconductivity in a heavy-fermion antiferromagnet CePt3Si has ignited remarkable interest in studying non-centrosymmetric (NCS) superconductors. The lack of an inversion center in this crystal structure induces an intrinsic electric field gradient that gives rise to antisymmetric spin-orbit coupling. As a result the spin degeneracy of electronic bands is lifted, which may develop parity-mixed superconducting state. We present our study on the weakly correlated Th-based alloys ThTSi (T = Co, Ni, Ir, Pt), crystallizing with a NCS structure like LaPtSi (a superconductor at TC = 3.35 K). We discuss the variation of superconducting transitions with transition metals based on our experimental results as well as band calculations. |
Tuesday, March 6, 2018 1:39PM - 1:51PM |
F31.00013: Superconducting Two-Dimensional Metal-Organic Framework Xiaoming Zhang, Yinong Zhou, Bin Cui, Mingwen Zhao, Feng Liu Superconductivity is a fascinating quantum phenomenon characterized by zero electrical resistance and the Meissner effect. To date, several distinct families of superconductors (SCs) have been discovered. These include 3D bulk SCs in both inorganic and organic materials as well as 2D thin film SCs but only in inorganic materials. Here we predict superconductivity in 2D and 3D organic metal-organic frameworks by using first-principles calculations. We show that the highly conductive and recently synthesized Cu-benzenehexathial (BHT) is a Bardeen-Cooper-Schrieffer SC. Remarkably, the monolayer Cu-BHT has a critical temperature (Tc) of 4.43 K while Tc of bulk Cu-BHT is 1.58 K. Different from the enhanced Tc in 2D inorganic SCs which is induced by interfacial effects, the Tc enhancement in this 2D organic SC is revealed to be the out-of-plane soft-mode vibrations, analogous to surface mode enhancement originally proposed by Ginzburg. Our findings not only shed new light on better understanding 2D superconductivity, but also open a new direction to search for SCs by interface engineering with organic materials. |
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