Magnetic excitations in the geometric frustrated multiferroic CuCrO2

Abstract

12In this paper detailed neutron scattering measurements of the magnetic excitation spectrum of CuCrO2 in the ordered state below TN1 = 24.2 K are presented. The spectra are analyzed using a model Hamiltonian which includes intralayer-exchange up to the next-next-nearest neighbor and interlayer-exchange. We obtain a definite parameter set and show that exchange interaction terms beyond the next-nearest neighbor are important to describe the inelastic excitation spectrum. The magnetic ground state structure generated with our parameter set is in agreement with the structure proposed for CuCrO2 from the results of single crystal diffraction experiments previously published. We argue that the role of the interlayer exchange is crucial to understand the incommensurability of the magnetic structure as well as the spin-charge coupling mechanism.

Development of Spin Correlations in the Geometrically Frustrated Triangular-Lattice Heisenberg Antiferromagnet CuCrO2

“…At 6 K, the spin-wave excitations dispersing from the magnetic Bragg peak positions (K points), Q = (1/3, 1/3) and (2/3, 2/3), were observed over ∼8 meV [ Fig. 1(a)], and the dispersion relation was consistent with previously reported results obtained at 2 K [15]. It should be noted that a continuum scattering with less intensity existed above the spin wave dispersion over ∼10 meV, which likely originated from two-magnon scattering [27].…”

“…This compound is similar to the ordered rock-salt compound NaCrO 2 in that the S = 3/2 spins of the Cr 3+ (3d 3 ) ions form a 2D triangular lattice, and the Cr layers stack in a rhombohedral manner (ABCABC · · ·) [11]. In this compound, 2D spin correlations begin to develop around the Curie-Weiss temperature T CW = 160-200 K [12][13][14][15][16]. Because of finite inter-layer couplings, three-dimensional (3D) ordering of a nearly 120 • structure occurs below T N ∼ 24 K [16][17][18].…”

“…The crystal was initially aligned such that c was parallel to the incident neutron beam and the [110] direction was horizontal, and then rotated about the vertical axis by 40 • . The Q z dependence of the data was ignored, because the magnetic excitations were quasi 2D [15,25], whereas the Q dependence was represented by the 2D hexagonal reciprocal lattice (Q x , Q y ) = (Ha * , Ka * ) with…”

Lattice dynamics and thermal transport in multiferroicCuCrO2

“…Thus, it presents an opportunity to study the direct coupling between the magnetic and ferroelectric order parameters [3,4]. A number of studies have investigated the crystal structure, magnetic excitations, magnetization, and electric polarization in CuCrO 2 [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], but little is known about the phonons and their coupling or response to the magnetic/ferroelectric ordering.…”

Static and Dynamical Properties of the Spin-1/2Equilateral Triangular-Lattice AntiferromagnetBa3CoSbMa1, Kamiya2, Hong3 et al. 2016Phys. Rev. Lett.Self Cite142201454View full textAdd to dashboardCite

“…The combination of frustration, strong quantum fluctuations and low dimensionality is anticipated to produce strong deviations from semiclassical theories. While several distorted triangular-lattice materials, such as κ-(BEDT-TTF) 2 Cu 2 (CN) 3 [15], Cs 2 CuX 4 (X = Cl [16][17][18] and Br [18][19][20]), and CuCrO 2 [21,22], have been investigated in the past, the distorted structures introduce additional terms, such as the Dzyaloshinskii-Moriya (DM) interaction, into the paradigmatic Hamiltonian [16][17][18][19][20]23].…”