Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session B38: 2D Magnetism IFocus
|
Hide Abstracts |
Sponsoring Units: GMAG DMP Chair: Mark Meisel, University of Florida Room: BCEC 206B |
Monday, March 4, 2019 11:15AM - 11:51AM |
B38.00001: Criticality in Two-Dimensional Quantum Antiferromagnets (2D QAF) Invited Speaker: Christopher Landee Low Dimensional (LoD) physics has long provided opportunities (both analytical and experimental) for exploring criticality in model systems that are more tractable than the more formidable 3D analogs. In particular, magnetic LoD compounds have provided multiple physical realizations with which theoretical predictions can be tested. The quantum (S = ½) two-dimensional model clearly reveals the influence of exchange anisotropy (Ising, XY, Heisenberg) and quantum fluctuations upon criticality: the Ising model spontaneously orders, the XY system undergoes a topological transition, and the Heisenberg analog (2D QHAF) remains disordered at any finite temperature. There are many crystalline compounds accurately described as 2D quantum Ising antiferromagnets but the equivalent XY and Heisenberg materials remain in development. |
Monday, March 4, 2019 11:51AM - 12:03PM |
B38.00002: Single crystal EPR analysis of pyrazine bridged layered complexes Jeffrey Monroe, Christopher Landee, Fredrick T Greenaway, Jan L Wikaira, Mark M Turnbull Over the last three decades our group has endeavored to model the antiferromagnetic interactions of the copper-oxide high-temperature superconductors via crystal engineering of low dimensional copper(II) systems. Our efforts have led us to systems of the type [Cu(pz)2(L)2](A)2 which contain well isolated pyrazine-bridged square-lattices with Heisenberg antiferromagnetic superexchange. We report primarily on [Cu(pz)2(2-hydroxypyridine)2](PF6)2. The single crystal EPR linewidth as a function of temperature and angle at X-Band are investigated in three orientations where XYZ≈abc. The linewidth is investigated in terms of g-anisotropy, dipolar spin-diffusion, antisymmetric and anisotropic exchange. The linewidth in the ac and bc planes follow a cos2(θ) dependence indicating the dominant contributions to the linewidth are the anisotropic and antisymmetric exchange1. These results are compared to those from other techniques including NMR and SQUID magnetometry. The effects of these interactions on the 3D ordering temperature are considered. |
Monday, March 4, 2019 12:03PM - 12:15PM |
B38.00003: Low-dimensional quantum magnets supported by non-covalent interactions Jamie Manson, Jacqueline Villa, Danielle Villa, William Blackmore, Robert Williams, Jamie Brambleby, Paul Goddard, John Singleton, Roger Johnson, Saul H. Lapidus, Benjamin Huddart, Thomas Hicken, Tom Lancaster, Steve Blundell, Fan Xiao, John Schlueter At ambient pressure, [Ni(HF2)(pyz)2]SbF6 contains S = 1 Ni(II) ions arranged in a tetragonal network consisting of 1D Ni-FHF-Ni chains (J) cross-linked by pyrazine (pyz) ligands (J’). Previous work determined D = 13.3 K, J = 10.4 K and J’ = 1.4 K [1]. Below TN = 12.2 K, long-range magnetic order sets in and, as revealed by neutron diffraction, is of the XY-type with Ni(II) moments occupying any collinear orientation in the crystallographic ab-plane. Pressure-dependent X-ray powder diffraction data reveal a first-order structural phase transition at 3 GPa which leads to a distorted monoclinic network and kinked magnetic exchange pathways. In this high-pressure regime, the magnetic ground state switches to Ising-like with concomitant reduction in TN. The related quasi-1D chain, NiI2(3,5-lutidine)4, also forms a tetragonal lattice but consiss of discrete molecular units. A chain-like motif affords close Ni-I...I-Ni contacts and strong magnetic coupling. Evidence suggests that this material is a rare isotropic Haldane chain with J = 17.5 K and D = 6.3 K [2]. Time permitting, structural and magnetic properties of each material will be presented. |
Monday, March 4, 2019 12:15PM - 12:27PM |
B38.00004: Magnetism in a novel quasi-2D honeycomb lattice S=3 antiferromagnet. Mojammel Alam Khan, Bao Zinke, Qiang Zhang, Randy Fishman, John Mitchell Honeycomb lattice antiferromagnets have been of tremendous research interests due to their complex magnetic structures ranging from Neél, zigzag, stripy, and spin liquid depending on details of competing exchange interactions. To study these interesting magnetic states, we have synthesized single crystals of a novel spin-3 honeycomb lattice antiferromagnet, Tb2Ir3Ga9, which is a member of a large family of compounds with chemical formula R2T3X9 (R = rare-earth element, T = d-element, and X = p-block element). Structural analysis showed the crystals have formed in orthorhombic symmetry with space group 63 (Cmcm). From the magnetization measurements, we find characteristics of low-dimensional magnetism followed by a long range ordering at 12 K. As determined both by magnetometry and powder neutron diffraction, the Tb spins lie strictly along the a-axis, parallel to the Tb-Tb contact. Two spin-flop transitions are observed when the field is applied parallel to this axis, separated by a plateau corresponding to M=Ms/2. Magnetoresistance data reflect the anisotropy and contains features that correlate with the spin flop transitions. We propose a model for the magnetic ground state and a phenomenological theory for the magnetic interactions. |
Monday, March 4, 2019 12:27PM - 12:39PM |
B38.00005: Study of magnetic properties of botallackite Cu2(OH)3Br with a distorted triangular lattice Heda Zhang, Zhiying Zhao, Vasile O Garlea, Tao Hong, Dominique Gautreau, Amartyajyoti Saha, S Mahanti, Turan Birol, Xianglin Ke Hydroxy halides M2(OH)3X (M = transition metal, X = Cl, Br, I) represent a family to investigate novel quantum phenomena arising from the magnetic frustration. For instance, via doing Zn into Cu sites in the parent cinoactacamite Cu2(OH)3Cl, herbertsmithite ZnCu3(OH)6Cl2 hosts a perfect two-dimensional kagome magnetic lattice and exhibits quantum spin liquid state without long range magnetic ordering. In this paper, we report a comprehensive study of botallackite Cu2(OH)3Br, a compound with distorted quasi-two dimensional triangular magnetic lattice, via magnetic susceptibility, heat capacity, neutron diffraction, and inelastic neutron scattering measurements. Density functional theory calculations to understand the exchange interactions of this system will be briefly discussed as well. |
Monday, March 4, 2019 12:39PM - 12:51PM |
B38.00006: A first-principles study of the magnetic behavior of the compound Cu2(OH)3Br Dominique Gautreau, Amartyajyoti Saha, Heda Zhang, Zhiying Zhao, S Mahanti, Xianglin Ke, Turan Birol The copper compound Cu2(OH)3Br has relatively few experimental studies, and, to the best of our knowledge, this material has not been approached from first principles before. Previous experimental work on the isostructural compound Cu2(OH)3Cl has demonstrated an interesting frustrated magnetic phase below the Neel temperature. Furthermore, upon substitution of the halogen ion, the Neel temperature was shown to grow with increasing halogen ion size for Cu2(OH)3Cl, Cu2(OH)3Br, and Cu2(OH)3I, possibly providing insight into the superexchange mechanism in this material. In this talk, we present the results of our first principles calculations on the compound Cu2(OH)3Br. We discuss the magnetic phase; in particular, we find the exchange constants and elucidate the interplay between magnetism and orbital configuration. |
Monday, March 4, 2019 12:51PM - 1:03PM |
B38.00007: Spin spirals from 120° antiferromagnetic states in transition-metal-deposited MoS2 Wuzhang Fang, Alexey Kovalev, Kirill Belashchenko Finding skyrmions in different kinds of structures has attracted a lot of attention but also remains a challenge. Here we study the adsorption of transition metal atoms (Cr, Mn, Fe, and Co) deposited on top of a monolayer MoS2 where the transition metal atoms form a triangular lattice. First-principles DFT calculations suggest that the magnetic ordering of this triangular lattice corresponds to a 120-degree antiferromagnetic structure. Heisenberg exchange parameters, single-ion anisotropy constants, and Dzyaloshinskii-Moriya vectors are extracted by choosing different spin configurations and calculating the total energy differences. For the considered transition metal atoms, the ground states are found to be spin spirals formed from 120-degree antiferromagnetic states. Our study shows the potential to find skyrmions in such triangular lattices. |
Monday, March 4, 2019 1:03PM - 1:15PM |
B38.00008: Orbital and Charge Participation in the Magnetic Phases of Intercalated Fe1/3TaS2, Fe1/3NbS2 and Their Alloys Conrad Stansbury, Claudia Fatuzzo, Eran Maniv, Spencer Doyle, Caolan John, James G. Analytis, Alessandra Lanzara The Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction has been used to understand the origin of (anti)ferromagnetic behavior in some magnetic transition metal intercalated dichalcogenides (TMDs). Despite the clean picture that RKKY presents, little has been said about the interplay of intercalate magnetism with the low temperature phases in disulfide TMDs. By using angle resolved photoemission spectroscopy (ARPES) and optical spectroscopies we are able to provide a new picture for the onset of magnetic phases over a family of transition metal intercalates on the basis of charge transfer. The interaction between magnetism and other forms of order in 2H-NbS2 and 2H-TaS2 will also be explored. |
Monday, March 4, 2019 1:15PM - 1:27PM |
B38.00009: Controlling and Tuning the Magnetic Ground State in an Intercalated Transition Metal Dichalcogenide Spencer Doyle, Caolan John, Eran Maniv, James G. Analytis It is possible to engineer magnetism in layered TMDs XS2 (X=transition metal) via intercalation of magnetic transition metals. In particular, iron intercalation (1/3 Fe per X site) introduces a two-dimensional magnetic sublattice between XS2 layers. Despite adopting identical crystal structures with near-identical lattice parameters, the magnetic ground states of Fe1/3NbS2 and Fe1/3TaS2 are antiferromagnetic and ferromagnetic, respectively. Due to their chemical similarity, these two materials can form end members of an alloying series Fe1/3Nb1-xTaxS2. Due to the different magnetic orderings of its end members, this alloying series permits the substitutional control of the magnetic ground state of the material system. I will present our thermodynamic measurements and findings. |
Monday, March 4, 2019 1:27PM - 1:39PM |
B38.00010: Anomalous Hall Effect Mechanisms in Quasi-2D van der Waals Ferromagnet Fe0.29TaS2 Ranran Cai, Wenyu Xing, Huibing Zhou, Yangyang Chen, Yunyan Yao, Yang Ma, Xincheng Xie, Shuang Jia, Wei Han
|
Monday, March 4, 2019 1:39PM - 1:51PM |
B38.00011: WITHDRAWN ABSTRACT
|
Monday, March 4, 2019 1:51PM - 2:03PM |
B38.00012: Local broken symmetry and spin transport in frustrated Heisenberg model in low dimension Leonardo dos Santos Lima The local spontaneous symmetry breaking is a general phenomena in condensed matter physics. It is characterized by the fact that the action has a local symmetry but the quantum theory, instead of having a unique vacuum state which respects this symmetry, has a family of degenerate vacua that transform into each other under the action of the symmetry group. A simple example is given by a ferromagnetic model in which the action governing its microscopic dynamics is invariant under spatial rotations. A kind of local gauge invariance or spontaneous breaking of U(1) gauge symmetry is realized in nature in the phenomenon of superconductivity. |
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