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 E54: Dichalcogenides and MetalsFocus Live
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Sponsoring Units: DMP Chair: Adam Aczel, Oak Ridge National Lab |
Tuesday, March 16, 2021 8:00AM - 8:12AM Live |
E54.00001: Electronic structure of the metallic oxide ReO3 Johannes Falke, Cheng-En Liu, Daisuke Takegami, Chun-Fu Chang, Chi-Sheng Chen, Li Zhao, Alexander Komarek, Chang-Yang Kuo, Chien-Te Chen, Liu Tjeng We have investigated the electronic structure of the metallic oxide ReO3 using bulk-sensitive angle-resolved soft-x-ray and angle-integrated hard-x-ray photoelectron spectroscopy. We observed clear dispersions of the Re 5d and O 2p derived bands as well as the momentum splitting of the Fermi surface due to the Re 5d spin-orbit interaction. We found that density-functional-based band-structure calculations can provide an accurate description of the observed electronic states. To achieve the accuracy it was necessary to take into account self-interaction effects in the calculations. |
Tuesday, March 16, 2021 8:12AM - 8:24AM Live |
E54.00002: Local electronic structure of RuO2 Connor Occhialini, Valentina Bisogni, Hoydoo You, Andi Barbour, Ignace Jarrige, John Mitchell, Riccardo Comin, Jonathan Pelliciari Despite being historically identified as a paramagnetic semi-metal, RuO2 has received heightened interest for its recently discovered itinerant antiferromagnetism, novel Hall effects and strain-induced superconductivity. Microscopic understanding and further manipulation of these properties demands resolving the relative roles of the unique rutile crystal field and 4d spin-orbit coupling in the electronic structure. In this talk, I will discuss recent results of M3-edge (3p-4d) resonant inelastic X-Ray scattering experiments on bulk RuO2. Through identification of the dd-excitations, their resonance behavior and comparison to multiplet calculations, we are able to place definitive constraints on the contributions of the low-symmetry crystal field and spin-orbit coupling in the local orbital energetics. Our results have implications for the balance of these interactions across the 3d, 4d and 5d rutile oxides and provide a path toward determining the local strain-induced orbital modifications which result in superconductivity. |
Tuesday, March 16, 2021 8:24AM - 8:36AM Live |
E54.00003: Machine Learning Analysis of Structural Order and Goldstone-Mode Fluctuations in Cd2Re2O7 Raymond Osborn, Eun-Ah Kim, Matthew Krogstad, Stephan Rosenkranz, Jordan M Venderley, Michael Matty, Kilian Q Weinberger, David George Mandrus Spin-orbit coupling in transition metal compounds with 4d and 5d electrons is predicted to generate a wide variety of novel parity-breaking correlated electron phases, but evidence of a concomitant structural response is often lacking. Cd2Re2O7 is a pyrochlore that has been proposed to exhibit multipolar nematic order below two structural phase transitions at 200K and 113K, but the symmetry of the order parameters are under dispute. We report high-energy x-ray scattering measurements of 3D reciprocal space volumes comprising over 10,000 Brillouin zones in a fine Q-grid performed at many temperatures from 300K to 30K. We have analyzed the data with unsupervised machine learning, using the newly-developed X-TEC algorithm [1], to classify the temperature dependence of both superlattice peaks and diffuse scattering. The order parameter below 200K results from cation displacements consistent with the condensation of a nearly-degenerate two-component Eu mode. X-TEC also identified diffuse scattering below 200K from Goldstone mode fluctuations between the two Eu modes, which could explain the lower transition at 113 K. |
Tuesday, March 16, 2021 8:36AM - 8:48AM Live |
E54.00004: Absolute microwave surface impedance of the delafossites: Simulations of non-ellipsoidal geometries Timothy Branch, Graham Baker, James Day, Douglas A. Bonn The delafossite metal PdCoO2, with its nearly hexagonal Fermi surface and exceptionally long, anisotropic electron mean free path, has exhibited an array of exotic DC transport phenomena [1]. Microwave cavity perturbation measurements of hexagonal platelet samples of PdCoO2 will allow the anisotropy of the absolute complex surface impedance to be precisely determined. These measurements of surface impedance will in turn allow for the predictions of non-local transport models to be tested, providing differentiation between the contributions of ballistic and hydrodynamic effects to AC electron dynamics in PdCoO2. |
Tuesday, March 16, 2021 8:48AM - 9:00AM Live |
E54.00005: Resonant Inelastic X-ray Scattering study of the charge density wave phase of 1T-TaS2 Alberto De La Torre, Tsung-Han Yang, Ben Zager, Diego M Casa, Mary Upton, Kemp Plumb The low temperature ground state of 1T-TaS2 continues to draw attention .The onset of a commensurate charge density wave (CDW) order results in a low energy electronic structure with an odd number of electrons per unit cell. Thus, the increasing resistivity and anomalously small magnetic susceptibility have been regarded as evidence for a Mott insulating phase that could host spin liquid physics [1]. However, there is growing evidence that cooling rate-dependent CDW [2] stacking faults can induce a much more trivial groundstate in bulk 1T-TaS2 [3]. Interestingly, recent scanning tunneling spectroscopy measurements revealed the existence of localized spins in mono-layer samples of isostructural 1T-TaSe2 [3]. Here we present our recent temperature-, Q- and energy-dependent Resonant Inelastic X-ray Scattering study at the Ta L3-edge of bulk 1T-TaS2. We discuss our results in relation to the proposed groundstate scenarios. |
Tuesday, March 16, 2021 9:00AM - 9:12AM Live |
E54.00006: Tuning Fork measurement on spin-orbit coupled metal Guoxin Zheng, Lu Chen, Kuan-Wen Chen, Ziji Xiang, Dechen Zhang, Jiaqiang Yan, David George Mandrus, Lu Li Spin-orbit-coupled metal Cd2Re2O7 has revealed several interesting phenomena, including the multipolar order and superconductivity. To understand these phenomena, the Landau Level quantization and quantum oscillation are essential. However, the early quantum oscillation pattern observed in torque magnetometry missed small orbits expected from the band structure calculation. To solve the problem, we applied tuning-fork-based torque differential magnetometry to search for the quantum oscillation patterns of the small Fermi Surface orbits in Cd2Re2O7. The torque differential magnetometry measures the derivative of the magnetic torque relative to the magnetic field tilt angles, thus becoming very sensitive to the anisotropy of Fermi Surfaces. We will also compare the resolved orbital sizes with those determined from torque magnetometry. |
Tuesday, March 16, 2021 9:12AM - 9:24AM Live |
E54.00007: Modeling a plethora of dimerized phases in IrTe2 Sergey Artyukhin, Francesco Foggetti, Louis Ponet, Daniel Khomskii IrTe2 is a one of the transition metal dichalcogenides with the structure containing triple triangular layers Te-Ir-Te with Ir ions in the octahedral coordination. Upon cooling below 220 K a sequence of phases with rows of Ir-Ir dimers are seen. Here we combine first principles calculations and a simplified model descibing the free energy of dimerized phases to compute the phase diagram and rationalize the emergence of these phases. |
Tuesday, March 16, 2021 9:24AM - 9:36AM On Demand |
E54.00008: Unconventional orbital-charge density wave mechanism in transition metal dichalcogenide 1T-TaS2 Toru Hirata, Youichi Yamakawa, Seiichiro Onari, Hiroshi Kontani The transition metal dichalcogenide 1T-TaS2 attracts growing attention because of the formation of rich density-wave (DW) and superconducting transitions. However, the origin of the incommensurate DW state below TIC≈550K, which is the ``parent state'' of the rich physical phenomena, are still uncovered. Here, we attack this fundamental problem by focusing on the spin-fluctuation-driven DW mechanism that has been developed in the study of Fe-based and cuprate superconductors [1-2]. We derive the optimized form factor, which is DW order parameter with momentum, orbital, and energy dependences, by applying the DW equation method developed in Refs. [1-2] to the eight-orbital Hubbard model for 1T-TaS2. The obtained triple-q orbital-charge DW state satisfactorily explains the incommensurate DW state in 1T-TaS2. The predicted orbital-selective form factor with unconventional sign-reversal in both momentum and energy spaces would be measurable by the ARPES study. The present study gives a fundamental information to understand the rich physics in 1T-TaS2. [1] S. Onari and H. Kontani, Phys. Rev. Lett. 109, 137001 (2012). [2] S. Onari and H. Kontani, Phys. Rev. Research 2, 042005 (2020). |
Tuesday, March 16, 2021 9:36AM - 10:12AM Live |
E54.00009: Chemistry Perspectives to Discover Novel Rare-Earth-Free Ferromagnetic Material with Strong Spin-Orbit Coupling Invited Speaker: Weiwei Xie Applying chemistry bonding concepts for finding novel quantum materials has been used in materials discovery. The novel family compounds APt5M (A= Mn and Fe; M= P and As) were designed and synthesized from a chemistry viewpoint. The crystal and magnetic structure characterizations show APt5M crystalizes in the anti-CeCoIn5 layered structure with 2D magnetic behaviors. Among them, MnPt5As shows ferromagnetic properties with the Tc ~287 K while MnPt5P is antiferromagnetic. According to the theoretical assessments, the 3d-5d hybridization and spin-orbit coupling on Pt are critical to their structural stability and magnetic properties. Moreover, by changing the atomic distances, we can successfully tune the magnetic properties of new materials. In this talk, I will discuss the family compounds. |
Tuesday, March 16, 2021 10:12AM - 10:24AM Live |
E54.00010: Using spin-orbit heavy metals as a probe for emergent phases in a honeycomb insulator Ella Lachman, Vikram Nagarajan, Hossein Taghinejad, James Analytis Materials with 5d and 4d orbitals host a plethora of intriguing properties stemming from the competition between different energy scale such as spin-orbit coupling, crystal-field energy, and exchange interactions. The intricate interplay between these interactions lead to frustration in the material and potentially to a realization of the Quantum Spin Liquid (QSL) state. |
Tuesday, March 16, 2021 10:24AM - 10:36AM Live |
E54.00011: Study of the spin orbit coupling metal Cd2Re2O7 by torque magnetometry Kuan-Wen Chen, Tomoya Asaba, Yang Zhang, Guoxin Zheng, Ziji Xiang, Colin B Tinsman, Lu Chen, Jiaqiang Yan, David George Mandrus, Liang Fu, Lu Li Cd2Re2O7 is the first superconductor in pyrochlore oxide family and a prototype compound for spontaneous inversion symmetry breaking with strong spin-orbit coupling. The inversion breaking transition near 200K from centrosymmetric cubic phase to the noncentrosymmetric tetragonal phase. Another structural transition occurs at 120K. However, the distortions are very small and identified controversially in different measurement techniques. Quantum oscillation is very sensitive to the differences of the structures and ideally to study the inversion symmetry breaking from spin splitting Fermi surfaces. In this talk, we will discuss the Fermiology of Cd2Re2O7 by torque magnetometry and compare with the density functional calculations. |
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