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 S41: Metals: Functional and ActinidesLive
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Sponsoring Units: DCMP Chair: Maohua Du, Oak Ridge National Lab |
Thursday, March 18, 2021 11:30AM - 11:42AM Live |
S41.00001: Coulomb correlation in noncollinear antiferromagnetic α-Mn Bernardo Barbiellini, Aki Pulkkinen, Johannes Nokelainen, Vladimir V Sokolovskiy, Danil Baigutlin, Olga Miroshkina, Mikhail Zagrebin, Vasiliy D Buchelnikov, Christopher Lane, Robert Markiewicz, Arun Bansil, Jianwei Sun, Katariina Pussi, Erkki Lähderanta We discuss the interplay between magnetic and structural degrees of freedom in elemental Mn. The equilibrium volume is shown to be sensitive to magnetic interactions between the Mn atoms. While the standard generalized gradient approximation underestimates the equilibrium volume, a more accurate treatment of the effects of electronic localization and magnetism is found to solve this longstanding problem. Our calculations also reveal the presence of a magnetic phase in strained α-Mn that has been reported previously in experiments. This new phase of strained α-Mn exhibits a noncollinear spin structure with large magnetic moments. Our results are relevant for smart materials such as the shape-memory and magnetocaloric Mn-rich Heusler alloys because elemental Mn and the Mn-rich Heusler alloys present phase diagrams with common features. |
Thursday, March 18, 2021 11:42AM - 11:54AM Live |
S41.00002: Intermediate Valence Behavior of Yb2Cu9Al8 Martin Juckel, Primoz Kozelj, Alim H Ormeci, Eteri Svanidze, Andreas Leithe-Jasper, Yurii Prots, Ulrich Burkhardt Intermediate valence behavior is frequently observed in compounds containing Ce, Yb, Eu, Sm, or Tm. In the current talk, I will discuss synthesis and characterization of an intermetallic compound Yb2Cu9Al8 which crystallizes in the Th2Zn17 structure type. An excitation energy Eex/kB of 319 K and a spin fluctuations temperature Tsf of 60 K are characteristic of its intermediate valence behavior, whereas the valence state of Yb is estimated to be close to 2.04 for the low-temperature region. The valence gradually evolves to the value of 2.80 at T = 400 K. The Sommerfeld coefficient of gexp = 59 mJ/molYb K2 indicates a moderate effective mass enhancement, together with a finite density of states at the Fermi level. The latter is also confirmed by the band structure calculations. |
Thursday, March 18, 2021 11:54AM - 12:06PM Live |
S41.00003: A scattering framework for linear magnetoresistance when the mean free path exceeds the length scale of disorder Christian Boyd, Philip Phillips Linear magnetoresistance, where the change in resistivity grows linearly with an applied magnetic field, has been observed in conductors ranging from polycrystalline elemental metals to Weyl semimetals to more recently high-Tc so-called strange metals. In previous work [1], the authors examined the linear magnetoresistance of a cuprate high-Tc superconductor within the framework of a classical disorder model, or when the disorder is within well-defined macroscopic quantities such as the local conductivity. A classical disorder model can just justified roughly when the mean free path is much smaller than the length scale governing inhomogeneity within a material; however, a new mechanism must be at play for low temperatures when the mean free path exceeds the length scale of any material inhomogeneity. It is precisely this latter regime which we investigate from a diagrammatic repeated-scattering framework in order to clarify the mechanism of linear magnetoresistance in disordered conductors beyond a classical framework. |
Thursday, March 18, 2021 12:06PM - 12:18PM Live |
S41.00004: Accelerating the discovery of bimetallic materials for sensing applications via DFT and ML Abdul Qadeer Rehan, Robert Malcolm Kent, Molly Kate Kreider, Anibal Thiago Bezerra, Mariama Rebello The use of metal alloys is a promising route to improve the performance of gas-, water-, and biosensors due to their ability to engineering physical properties such as the dielectric function. To determine the best composition for a particular application, traditional methods use repeated rounds of material synthesis and characterization with high costs. Alternatively, simulation and modeling methods have enabled the expansion of databases that cover the calculated properties of known and hypothetical systems. However, evaluating the alloys' dielectric response by the independent particle approximation using DFT with adjustable smearing parameters for the inter- and intraband transitions is a rather time-consuming task. To overcome this challenge, we designed an artificial neural network trained to predict an Al-Au system's dielectric response. To confirm our prediction, we fabricated bimetallic films with different compositions and measured their optical properties at different temperatures. We find a 97% accuracy for the ML, with a time reduction of the calculation form weeks to less than one hour. Moreover, we show that all alloys outperform their pure counterparts in sensitivity, with Au0.85Al0.15 being the best candidate for replacing pure gold in SPR sensors. |
Thursday, March 18, 2021 12:18PM - 12:30PM Live |
S41.00005: PdRuIr Ternary alloy as an Effective NO Reduction Catalyst: Insights from First Principles Calculation Susan Aspera, Ryan L Arevalo, Hiroshi Nakanishi, Hideaki Kasai NO reduction is relevant in different catalytic reactions, particularly, in the three-way catalyst conversion system of automobile gas exhaust purification. NO dissociation is an important reaction step for NO reduction reaction. In this study, we used first principles calculation based on density functional theory to analyze NO interaction and dissociation on the ternary alloy PdRuIr. Ru catalysts are known to easily dissociate NO, however it also tends to easily form volatile oxides that compromises its stability. On the other hand, the PdRuIr ternary alloy combination benefits from Ru atoms catalytic ability to dissociate NO while weakening O adsorption, thereby making the surface relatively stable against formation of volatile RuOx while maintaining catalytic activity. |
Thursday, March 18, 2021 12:30PM - 12:42PM Live |
S41.00006: Controlling properties by chemistry in doped shape memory alloys Nikolai Zarkevich, Othmane Benafan, John Walter Lawson Shape memory alloys find increasing use in airspace applications. Using theoretical and computational methods, we investigate correlations between the selected properties and composition in doped NiTi-based shape memory alloys. Among the properties we consider relative energies, phase transition temperature, and hysteresis. We compare predictions to experimental data. Our theoretical guidance facilitates design of future alloys. |
Thursday, March 18, 2021 12:42PM - 12:54PM Live |
S41.00007: Plasmon-related electric effects in various plasmonic materials David Keene, Mohammad Shahabuddin, Tejaswini Ronur Praful, Maxim Durach, Natalia Noginova
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Thursday, March 18, 2021 12:54PM - 1:06PM Live |
S41.00008: Itinerant ferromagnetism mediated by giant spin polarization of metallic ligand band in van der Waals magnet Fe5GeTe2 Kohei Yamagami, Yuita Fujisawa, Benjamin D Driesen, Chia-Hsiu Hsu, Kaisyu Kawaguchi, Hiroki Tanaka, Takeshi Kondo, Yujun Zhang, Hiroki Wadati, Kosei Araki, Takahito Takeda, Yukiharu Takeda, Takayuki Muro, Feng-chuan Chuang, Yasuhiro Niimi, Kenta Kuroda, Masaki Kobayashi, Yoshinori Okada There is a growing interest in searching for new magnetism in van der Waals (vdW) compounds. In particular, one of the most important issues is to understand the mechanism of low-dimensional itinerant ferromagnetism. Very recent studies on ferromagnetic insulators of vdWs suggest that spin polarization of nonmagnetic ligands induced by hybridization with magnetic elements plays an important role in ferromagnetism[1,2]. In this study, we focused on vdW ferromagnetic metals at room-temperature Fe5GeTe2[3] and investigated element-specific electronic states by soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES) and soft X-ray magnetic circular dichroism (XMCD). |
Thursday, March 18, 2021 1:06PM - 1:18PM Live |
S41.00009: Antiferromagnetic ordering and 5f-electron localization in metallic PuPdSn Krzysztof Gofryk, Jean-Christophe Griveau, Eric Colineau, Roberto G. M. Caciuffo, James L. Smith While the effect of electronic correlations is relatively well studied in Ce, Yb and U based materials, there is still lack of knowledge on how these collective phenomena impact magnetic, transport, and thermodynamic properties in transuranium intermetallics. Depending upon the strength of the interactions, many unusual properties such as complex magnetism, Kondo effect, heavy fermion ground state, valence fluctuations, and/or unconventional superconductivity have been observed in these materials. Here we present our detailed studies on the structural, magnetic, thermal, and transport properties of PuPdSn. This compound crystalizes in the hexagonal ZrNiAl-type of structure [space group P62m]. It orders antiferromagnetically at TN = 21 K that is followed by another AF-like transition at 9.6 K. The low-temperature linear specific heat coefficient is small, γ∼8 mJ/mol K2. All the results obtained strongly suggest the presence of well localized 5f-states in this material, which is rare among U and Pu intermetallics. |
Thursday, March 18, 2021 1:18PM - 1:30PM Live |
S41.00010: Magnetic, transport and thermal properties of δ-phase UZr2 Xiaxin Ding, Kaya Wei, Zilong Hua, Chris Marianetti, Ryan Baumbach, David H. Hurley, Krzysztof Gofryk Recently, there has been a renewed interest in the U-Zr system due to its technological importance as a promising metallic nuclear fuel. Polycrystals of hexagonal δ-phase UZr2 have been synthesized and studied by means of heat capacity, magnetic susceptibility, magnetization, electrical resistivity, magnetoresistance, thermoelectric power, thermal conductivity measurements at temperatures from 0.1 to 300 K, and in magnetic fields up to 9T. The system exhibits a delocalized nature of 5f-electrons with the presence of significant electronic disorder, consistent with the disordered type of its crystal structure. Furthermore, characteristic behaviors of low-temperature electrical resistivity and heat capacity are consistent with the presence of the non-magnetic Kondo effect in this material. Density functional theory calculations have been performed and compared to experimental results. |
Thursday, March 18, 2021 1:30PM - 1:42PM Live |
S41.00011: Magnetoelectronic and optical properties of CoMnZnSi quaternary Heusler alloy Ramesh Paudel, Gopi Kaphle, Jing-Chuan Zhu, Durga Paudyal The structural stability, fully spin-polarized electronic structure, and optical properties of CoMnZnSi quaternary Heusler alloy in the bulk form as well as (111)-slab have been investigated on the basis of the density functional theory (DFT). Formation energy, cohesive energy, and elastic constants confirmed that the bulk CoMnZnSi is thermodynamically and mechanically stable at an optimized lattice parameter of 5.81 Å. The atomic relaxation and surface energies are predicted for the (111)-slab of the CoMnZnSi alloy. The results indicate that the Co (111), Mn (111), Zn (111), and Si (111)-slabs are thermodynamically stable. The bulk CoMnZnSi has shown a perfect half-metallic behavior with an integer value of magnetic moment (4 µB) and unexpectedly large spin-flip gap of 0.39 eV, while Co (111) and Si (111)-slabs have shown semi-metallic nature at the Fermi level. Therefore, this Heusler alloy can be a promising candidate material for spintronic applications. Optical properties, including conductivity, dielectric functions, reflectivity, absorption, refractive index, and loss function, are investigated from the complex dielectric function relation. |
Thursday, March 18, 2021 1:42PM - 1:54PM Live |
S41.00012: Thermodynamic and surface properties of Al–Li–Mg liquid alloy Arjun Dhungana, Shashit Kumar Yadav, Devendra Adhikari The theoretical calculation was carried out for thermo-physical functions, such as excess Gibbs free energy of mixing, activity, enthalpy of mixing, and surface tension, for liquid Al–Li-Mg ternary alloy at temperatures 1000 K, 1073 K, 1150 K, and 1250 K for the production of a thermodynamic database. For this purpose, the T-dependent interaction parameters of Redlich-Kister (R–K) polynomials for binary sub-systems were optimized, which were used to compute the excess Gibbs free energy of mixing for liquid Al–Li–Mg ternary alloy based on GSM, Toop, and Kohler models. The computed partial excess Gibbs free energy of mixing were used to determine the activities of the monomers of the binary sub-systems and ternary Al–Li–Mg system. The exponential T- dependent parameters have been optimized and used to calculate the enthalpy of mixing for the ternary system. Using the theoretically determined partial excess Gibbs free energy of constituent elements of the alloy, the surface tensions of binary sub-systems were calculated employing Butler’s equations. Further, the coefficients of T- dependent R–K polynomials have been optimized for excess surface tensions of binary subsystems, which were used to compute the surface tension of the ternary system using the models mentioned above. |
Thursday, March 18, 2021 1:54PM - 2:06PM Live |
S41.00013: Non-local microwave electrodynamics in PdCoO2 Graham Baker, James Day, Seunghyun Khim, Mohamed Oudah, Roderich Moessner, Joerg Schmalian, Andrew Mackenzie, Douglas A. Bonn The delafossite metal PdCoO2 has been shown to exhibit an array of exotic DC transport phenomena due to its exceptionally long mean free path and nearly hexagonal Fermi surface [1]. Here we present AC microwave spectroscopy measurements in two geometries for which, from the symmetry of the crystallographic lattice, one would conventionally expect the same result. Instead, the two measurements differ strongly in magnitude and frequency dependence. This is evidence for non-local electrodynamics, in which the mean free path is longer than the electromagnetic penetration depth and the conductivity is wavevector-dependent. While the theoretical description of non-local electrodynamics has historically been rooted in ellipsoidal Fermi surfaces [2], here we discuss how the strongly-faceted Fermi surface of PdCoO2 results in novel phenomenology. |
Thursday, March 18, 2021 2:06PM - 2:18PM Live |
S41.00014: Resonant inelastic x-ray spectroscopy (RIXS) on UO2 - a test case for actinide materials Martin Sundermann, Gerard H Lander, Ross Springell, Andrew Walters, Abhishek Nag, Mirian Garcia-Fernnandez, Ke-jin Zhou, Gerrit Van der Laan, Roberto G. M. Caciuffo A successful soft x-ray resonant inelastic x-ray spectroscopy (RIXS) experiment of UO2 at the U N4 absorption edge (778 eV) will be presented [1]. The RIXS spectra exhibit well resolved excitations due to the crystal-field splitting of the U4+ 5f 2 J=4 (3H4) Hund's rule ground state, and they show the first excited multiplet (3F2) at 550 meV. In RIXS the 3H4→3F2 transition has a strong cross-section due to the beyond dipole features of the RIXS process which is in strong contrast to the dipole cross-section of inelastic neutron scattering. Hence, the present experiment settles the discussion about the U4+ multiplet splitting in UO2. The data are simulated with a full multiplet RIXS calculation, taking into account the RIXS cross-section. |
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