ESR Modes in CsCuCl<sub><b>3</b></sub>

Tanaka, Hidekazu; Schotte, U.; Schotte, K. D.

doi:10.1143/jpsj.61.1344

Cited by 61 publications

(46 citation statements)

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“…As the magnetic field increases, the energy of the ω + mode increases and tends to approach the EPR line with g = 3.87, whereas the energy of the ω − mode decreases monotonically toward zero. The field evolutions of the ω + and ω − modes for H c are characteristic of the triangularlattice antiferromagnet with the easy-plane anisotropy rather than the easy-axis one [26][27][28]. If the anisotropy is of the easy-axis type, no degeneracy of the ω + and ω − modes occurs at zero magnetic field.…”

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confidence: 95%

Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2
Susuki
¹
,
Kurita
²
,
Tanaka
³

et al. 2013
Phys. Rev. Lett.
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We have performed high-field magnetization and ESR measurements on Ba3CoSb2O9 single crystals, which approximates the two-dimensional (2D) S = 1/2 triangular-lattice Heisenberg antiferromagnet. For an applied magnetic field H parallel to the ab-plane, the entire magnetization curve including the plateau at one-third of the saturation magnetization (Ms) is in excellent agreement with the results of theoretical calculations except a small step anomaly near (3/5)Ms, indicative of a theoretically undiscovered quantum phase transition. However, for H c, the magnetization curve exhibits a cusp near Ms/3 owing to the weak easy-plane anisotropy and the 2D quantum fluctuation. From a detailed analysis of the collective ESR modes observed in the ordered state, combined with the magnetization process, we have determined all the magnetic parameters including the interlayer and anisotropic exchange interactions.PACS numbers: 75.10. Jm, 75.45.+j, 75.60.Ej, Over the past decades, there has been considerable interest in frustrated quantum magnets, owing to a rich variety of exotic quantum phenomena [1][2][3]. For classical spins with an antiferromagnetic coupling, a geometric frustration suppresses the long-range ordering, leading to a degenerate ground state. The degeneracy can be destroyed by quantum fluctuations, which emerge not only through an interplay of strong geometric frustration, low dimensionality, and small spin, but also through the application of a magnetic field. Despite intensive research efforts, the detailed mechanism of the quantum effects, e.g., the ground state property [4,5], has still been highly controversial.One macroscopic manifestation of the quantum phenomena is the stabilization of the "up-up-down" spin structure under a magnetic field, predicted for a twodimensional (2D) triangular-lattice Heisenberg antiferromagnet (TLHAF) with a small spin [6,7]. In a magnetization process, the nonclassical anomaly appears as a plateau in a finite field range at one-third of the saturation magnetization M s , hereafter referred to as the M s /3 plateau. In a classical picture, a monotonic increase in the magnetization is expected up to M s . A number of theoretical approaches for explaining the quantum mechanism of the M s /3 plateau have been proposed [8][9][10][11][12][13][14]. Thus far, however, few numbers of definite experimental results reserved judgment on the issue. This is mainly due to the experimental difficulty in growing the model material, let alone in observing the M s /3 plateau purely driven by quantum fluctuations. In fact, most of the TLHAFs ever studied, such as Cs 2 CuBr 4 , [15,16] have a distorted triangular lattice, which induces an antisymmetric Dzyaloshinsky-Moriya (DM) interaction.It is believed that the spin state in the lower-field range above the higher edge field of the M s /3 plateau is the 2 : 1 canted coplanar state that is a continuous variant of the up-up-down state [7][8][9][10][11]. However, whether the 2 : 1 canted coplanar state is stable up to the saturation or a new quan...

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Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2
Susuki
¹
,
Kurita
²
,
Tanaka
³

et al. 2013
Phys. Rev. Lett.
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“…The S = 1/2 spins of the Cu 2+ ions form ferromagnetically coupled chains along the c-axis with J 0 = 28 K [4]. The chains are antiferromagnetically coupled and form a triangular lattice in the ab-plane, leading to a 120• spin structure below T N = 10.7 K at zero field [5]: the coupling strength is estimated to J 1 = -4.9 K [7]. The Curie-Weiss temperature obtained by the high-temperature magnetic susceptibility is comparable to T N for the magnetic fields along and perpendicular to the triangular lattice [1,6].…”

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confidence: 99%

Magnetic field induced polar phase in the chiral magnetCsCuCl3

Miyake¹,

Shibuya²,

Akaki³

et al. 2015

Phys. Rev. B

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Magnetoelectric effects in the chiral magnet CsCuCl3 have been investigated through the magnetization and electric polarization measurements in pulsed high magnetic fields. If the magnetic field is applied normal to the spin chiral c-axis, a plateau and a jump in magnetization are observed. Between the plateau and the jump in magnetization, a small but significant electric polarization of about 0.25 µC/m 2 along the a-axis is observed with the field applied almost perpendicular to the ac-plane. In addition, the paramagnetoelectric effect expected from the point group symmetry is confirmed. The emergence of the electric polarization is explained by the cooperation of the local electric polarization on the chiral solitonic spin arrangement and the paramagnetoelectric effect. Hence, we interpret this novel multiferroic phase in CsCuCl3 as a polar solitonic phase.PACS numbers: 75.30.Kz, 75.85.+t Various triangular lattice antiferromagnets (TAFM) have long been studied with the focus on their geometric frustration from the antiferromagnetic coupling of the neighboring spins on a triangular lattice [1][2][3]. Among the TAFM systems, a hexagonal CsCuCl 3 has received sustained interest because of its distinctive chiral crystal structure and its resultant magnetism under applied magnetic fields. The S = 1/2 spins of the Cu 2+ ions form ferromagnetically coupled chains along the c-axis with J 0 = 28 K [4]. The chains are antiferromagnetically coupled and form a triangular lattice in the ab-plane, leading to a 120• spin structure below T N = 10.7 K at zero field [5]: the coupling strength is estimated to J 1 = -4.9 K [7]. The Curie-Weiss temperature obtained by the high-temperature magnetic susceptibility is comparable to T N for the magnetic fields along and perpendicular to the triangular lattice [1,6]. One of the most striking characteristics in CsCuCl 3 is that the Cu-chains are displaced helically in the triangular plane because of the cooperative Jahn-Teller distortion below 423 K [8]: the Cu-chains form helices along the c-axis with a six-ion periodicity [see Fig. 4(b)] [9]. Depending on the chirality, CsCuCl 3 has space group of P 6 1 22 or P 6 5 22 (i.e., point group 622) [10]. The absence of inversion symmetry makes the Dzyaloshinskii-Moriya (DM) interaction active: the strength is estimated to D = 5 K [5], which is comparable with J 1 . The ferromagnetic (FM) interaction tends to align spin moments, whereas the DM interaction favors perpendicular arrangements of adjacent spins. The resultant spin configuration for CsCuCl 3 is helical arising from the competition of these interactions with a period of 11.8c [5].

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“…They analyzed the data without taking the D-M interaction into consideration. Tanaka et al 18) demonstrated that the ESR results can be described in accordance with the spin structure determined by the neutron scattering experiment.…”

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confidence: 57%

“…12,[16][17][18][19][20][21][22][23][24][25] Our discussion is confined mainly to the ground state properties. As shown below, a variety of ESR modes were observed in TAFs.…”

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confidence: 99%

Electron Spin Resonance in Triangular Antiferromagnets

et al. 2003

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We give an overview of our studies on the electron spin resonance (ESR) in the hexagonal triangular antiferromagnets of ABX 3 type using millimeter and submillimeter waves and static and pulsed high magnetic fields. Novel ESR modes, which cannot be understood by the conventional theory of the antiferromagnetic resonance, were observed. Examples of this include that there exists the gapless excitation even for the easy-axis anisotropy. The ESR modes can be classified by the signs of the exchange interaction J 0 along the c-axis and the anisotropy. The ESR modes were calculated within the framework of the mean-field approximation using threesublattice and six-sublattice models for the ferromagnetic and antiferromagnetic J 0 interaction, respectively. The experimental results were well described by the present calculations.KEYWORDS: ESR, triangular antiferromagnet, spin wave, antiferromagnetic resonance, frustration, hexagonal ABX 3 antiferromagnet §1. IntroductionSpin waves are beautiful collective excitations in magnetic systems. From the dispersion relations, we can know the exchange interactions, the magnetic anisotropies, the dimensionality of the system and so on. Neutron inelastic scattering and electron spin resonance (ESR) are powerful tools to observe the spin waves. Neutron inelastic scattering can excite the spin waves with various wave number Q, while the ESR can excite only Q = 0 modes. However, the ESR has the much higher resolution. Furthermore, using the millimeter and submillimeter waves ESR combined with pulsed high magnetic field, can observe the evolution of spin wave energies with magnetic field in the wide field range.The antiferromagnetic resonance (AFMR) is the ESR in the antiferromagnets, in which the spin structure can be described by two sublattices. The theory of AFMR has been established many years ago, 1-10) and were confirmed experimentally in many antiferromagnets. Figure 1 illustrates the frequency versus field diagrams of the AFMR modes for the uniaxial and biaxial anisotropies. For the uniaxial easy-axis and biaxial anisotropies, there is finite zero-field gap, while no zero-field gap exists for the uniaxial easy-plane anisotropy.For triangular antiferromagnets (TAF), little was known on the ESR modes.11) This seems because there was little suitable model substance and there was no standard theory. The comprehensive studies of the ESR * E-mail address: tanaka@lee.phys.titech.ac.jp. modes in the TAF started in the late 1980's on the hexagonal antiferromagnets of ABX 3 type with the CsNiCl 3 structure. 12-14)In the hexagonal antiferromagnets of ABX 3 -type, magnetic B 2+ ions form infinite chains along the crystallographic c-axis and triangular lattices in the basal c-plane, as shown in Fig. 2. Figure 3 shows the exchange interactions in the hexagonal antiferromagnets of ABX 3 -type. The intrachain interaction J 0 is stronger than the others. Thus, the present system exhibits the one-dimensional character at high temperatures. However, they behave as TAF at low temperatures, becau...

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ESR Modes in CsCuCl₃

Cited by 61 publications

References 17 publications

Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2
Susuki
¹
,
Kurita
²
,
Tanaka
³

et al. 2013
Phys. Rev. Lett.
Self Cite
223
27
264
1
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Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2
Susuki
¹
,
Kurita
²
,
Tanaka
³

et al. 2013
Phys. Rev. Lett.
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223
27
264
1
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Magnetic field induced polar phase in the chiral magnetCsCuCl3

Electron Spin Resonance in Triangular Antiferromagnets

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ESR Modes in CsCuCl3

Cited by 61 publications

References 17 publications

Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2Susuki1, Kurita2, Tanaka3 et al. 2013Phys. Rev. Lett.Self Cite223272641View full textAdd to dashboardCite

Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2Susuki1, Kurita2, Tanaka3 et al. 2013Phys. Rev. Lett.Self Cite223272641View full textAdd to dashboardCite

Magnetic field induced polar phase in the chiral magnetCsCuCl3

Electron Spin Resonance in Triangular Antiferromagnets

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ESR Modes in CsCuCl₃

Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2
Susuki
¹
,
Kurita
²
,
Tanaka
³

et al. 2013
Phys. Rev. Lett.
Self Cite
223
27
264
1
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Magnetization Process and Collective Excitations in theS=1/2Triangular-Lattice Heisenberg AntiferromagnetBa3CoSb2
Susuki
¹
,
Kurita
²
,
Tanaka
³

et al. 2013
Phys. Rev. Lett.
Self Cite
223
27
264
1
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