Browsing by Author "Matan, K"
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- ItemErratum: Magnetic structure and dzyaloshinskii-moriya interaction in the S=1/2 helical-honeycomb antiferromagnet α−Cu2V2O7 [Phys. Rev. B 92, 024423 (2015)](American Physical Society, 2017-03-10) Gitgeatpong, G; Zhao, Y; Avdeev, M; Piltz, RO; Sato, TJ; Matan, KNo abstract available. See the original item at: https://apo.ansto.gov.au/dspace/handle/10238/10250
- ItemMagnetic properties and magnetic structure of the frustrated quasi-one-dimensional antiferromagnet SrCuTe2O6(American Physical Society, 2020-10-07) Saeaun, P; Zhao, Y; Piyawongwatthana, P; Sato, TJ; Chou, FC; Avdeev, M; Gitgeatpong, G; Matan, KMagnetization measurements on single-crystal cubic SrCuTe2O6 with an applied magnetic field along three inequivalent high symmetry directions [100], [110], and [111] reveal weak magnetic anisotropy. The fits of the magnetic susceptibility to the result from a quantum Monte Carlo simulation on the Heisenberg spin-chain model, where the chain is formed via the dominant third-nearest-neighbor exchange interaction J3, yield the intrachain interaction (J3/kB) between 50.12(7) K for the applied field along [110] and 52.5(2) K along [100] with about the same g factor of 2.2. Single-crystal neutron diffraction unveils the transition to the magnetic ordered state as evidenced by the onset of the magnetic Bragg intensity at TN1=5.25(9)K with no anomaly of the second transition at TN2 reported previously. Based on irreducible representation theory and magnetic space group analysis of powder and single-crystal neutron diffraction data, the magnetic structure in the Shubnikov space group P4132, where the Cu2+S=1/2 spins antiferromagnetically align in the direction perpendicular to the spin chain, is proposed. The measured ordered moment of 0.52(6)μB, which represents 48% reduction from the expected value of 1μB, suggests the remaining influence of frustration resulting from the J1 and J2 bonds. ©2020 American Physical Society
- ItemMagnetic properties of the S = 1/2 antiferromagnetic spin-chain α - Cu2V2O7(American Physical Society, 2015-03-06) Gitgeatpong, G; Zhao, Y; Avdeev, M; Piltz, RO; Sato, TJ; Matan, KMagnetic properties of the S = 1 / 2 antiferromagnetic spin-chain, α - Cu2V2O7, have been studied using magnetization and neutron scattering measurements on powder and single-crystal samples. Magnetic susceptibility reveals a Curie-Weiss temperature of Θ = -73.2(9) K with a magnetic phase transition at TN = 33 K while the Bonner-Fisher fit to the magnetic susceptibility for T >TN with magnetic field perpendicular to the crystallographic a - axis yields the intra-chain coupling of |J|/k = 46.0(2) K. Small ferromagnetism below TN is due to spin-canting caused by Dzyaloshinskii-Moriya interactions. Analysis of the neutron diffraction data reveals that the Cu2+ spins are coupled antiferromagnetically along zigzag chains, which run alternately along [011] and [01-1] directions. The ordered moment of 0.925(3) μB is predominantly along the a - axis. Our recent inelastic neutron scattering, which reveals atypical magnetic excitations centered at commensurate wave vectors (0, +/-0.25, 0) around the magnetic zone center, will also be discussed. © 2021 American Physical Society
- ItemMagnetic structure and dzyaloshinskii-moriya interaction in the S=12 helical-honeycomb antiferromagnet α−Cu2V2O7(American Physical Society, 2015-07-23) Gitgeatpong, G; Zhao, Y; Avdeev, M; Piltz, RO; Sato, TJ; Matan, KMagnetic properties of the S=12 antiferromagnet α−Cu2V2O7 have been studied using magnetization, quantum Monte Carlo (QMC) simulations, and neutron diffraction. Magnetic susceptibility shows a broad peak at ∼50K followed by an abrupt increase indicative of a phase transition to a magnetically ordered state at TN=33.4(1) K. Above TN, a fit to the Curie-Weiss law gives a Curie-Weiss temperature of Θ=−73(1) K suggesting the dominant antiferromagnetic coupling. The result of the QMC calculations on the helical-honeycomb spin network with two antiferromagnetic exchange interactions J1 and J2 provides a better fit to the susceptibility than the previously proposed spin-chain model. Two sets of the coupling parameters J1:J2=1:0.45 with J1=5.79(1) meV and 0.65:1 with J2=6.31(1) meV yield equally good fits down to ∼TN. Below TN, weak ferromagnetism due to spin canting is observed. The canting is caused by the Dzyaloshinskii-Moriya interaction with an estimated bc-plane component |Dp|≃0.14J1. Neutron diffraction reveals that the S=12Cu2+ spins antiferromagnetically align in the Fd′d′2 magnetic space group. The ordered moment of 0.93(9) μB is predominantly along the crystallographic a axis. ©2015 American Physical Society
- ItemSodium layer chiral distribution and spin structure of Na2Ni2TeO6 with a Ni honeycomb lattice(American Physical Society, 2017-03-08) Karna, SK; Zhao, Y; Sankar, R; Avdeev, M; Tseng, PC; Wang, CW; Shu, GJ; Matan, K; Guo, GY; Chou, FCThe nature of Na ion distribution, diffusion path, and the spin structure of P2-type Na2Ni2TeO6 with a Ni honeycomb lattice has been explored. The nuclear density distribution of Na ions reveals a two-dimensional (2D) chiral pattern within Na layers without breaking the original 3D crystal symmetry, which has been achieved uniquely via an inverse Fourier transform (iFT)-assisted neutron-diffraction technique. The Na diffusion pathway described by the calculated isosurface of the Na ion bond valence sum (BVS) map is found consistent to a chiral diffusion mechanism. The Na site occupancy and Ni2+ spin ordering were examined in detail with the neutron diffraction, magnetic susceptibility, specific heat, thermal conductivity, and transport measurements. Signatures of both strong incommensurate (ICM) and weak commensurate (CM) antiferromagnetic (AFM) spin ordering were identified in the polycrystalline sample studied, and the CM-AFM spin ordering was confirmed by using a single-crystal sample through the k scan in the momentum space corresponding to the AFM peak of (12,0,1). © 2017 American Physical Society