Fluctuation-induced phase in in a transverse magnetic field: experiment

Schotte, U.; Kelnberger, A; Stüßer, N.

doi:10.1088/0953-8984/10/28/018

Cited by 23 publications

(42 citation statements)

References 18 publications

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“…With increasing H, δ decreases to ∼0.05 at the beginning of the M -plateau [13]. This region is referred to as the IC1 phase [15,17]. In the plateau region, δ is locked to this value independent of temperature [13,15].…”

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confidence: 99%

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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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“…• spin structure was discovered [17]. Although there are several high-field experiments [11,[13][14][15][16] and theoretical studies [18,19] on the magnetic transitions in fields normal to the c-axis, all aspects of these fascinating properties have not yet been revealed.…”

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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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“…22,[60][61][62][63][64][65][66][67][68][69][70] The Cu 2+ ion is Jahn-Teller active, when it is surrounded octahedrally by anions. For this reason, CsCuCl 3 undergoes a structural phase transition at T t = 423 K. For T < T t , CuCl 6 octahedra are elongated along the one of the principal axes and the elongated axes form a helix along the c-axis with a repeat length of six.…”

Section: Cscuclmentioning

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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“…Among the group of antiferromagnets which have a hexagonal ABX 3 triangular structure, many experimental and theoretical investigations for CsCuCl 3 have been done by several authors , [1][2][3][4] due to the remarkable features of this compound. Since the Cu 2+ ion is JahnTeller active, CsCuCl 3 undergoes a structural phase transition at T t = 423 K, where Jahn-Teller distorted octahedra CuCl 6 order so that their longest axes form a helix along the c-axis with a repeatlength of six .…”

Section: §1 Introductionmentioning

confidence: 99%

“…Single crystals of CsCu 1−x Co x Cl 3 were prepared by the Bridgman method from the melt of the single crystals of CsCuCl 3 and CsCoCl 3 . The details of the sample preparation are described in the previous paper.…”

Section: §1 Introductionmentioning

confidence: 99%

Oblique triangular antiferromagnetic phase inCsCu1−xCoxCl

et al. 2001

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The spin-1 2 stacked triangular antiferromagnet CsCu1−xCoxCl3 with 0.015 < x < 0.032 undergoes two phase transitions at zero field. The low-temperature phase is produced by the small amount of Co 2+ doping. In order to investigate the magnetic structures of the two ordered phases, the neutron elastic scattering experiments have been carried out for the sample with x ≈ 0.03. It is found that the intermediate phase is identical to the ordered phase of CsCuCl3, and that the low-temperature phase is an oblique triangular antiferromagnetic phase in which the spins form a triangular structure in a plane tilted from the basal plane. The tilting angle which is 42 • at T = 1.6 K decreases with increasing temperature, and becomes zero at TN2 = 7.2 K. An off-diagonal exchange term is proposed as the origin of the oblique phase. §1. Introduction Among the group of antiferromagnets which have a hexagonal ABX 3 triangular structure, many experimental and theoretical investigations for CsCuCl 3 have been done by several authors , 1-4) due to the remarkable features of this compound. Since the Cu 2+ ion is JahnTeller active, CsCuCl 3 undergoes a structural phase transition at T t = 423 K, where Jahn-Teller distorted octahedra CuCl 6 order so that their longest axes form a helix along the c-axis with a repeatlength of six . 5-7) The low-symmetric crystal structure produces the antisymmetric interaction of the Dzyaloshinsky-Moriya (D-M) type between the adjacent spins in the chain with the Dvector parallel to the c-direction. The exchange interactions along and between the chains are ferromagnetic and antiferromagnetic, respectively, and their values have been evaluated as J 0 /k B = 28 K and J 1 /k B = −4.9 K 8, 9) in the definition of H = − 2J ij S i · S j . The magnetic phase transition occurs at T N = 10.5 K . 10, 11) In the ordered state, spins lie in the basal plane and form the 120 • -structure, while along the c-direction, a long period (about 71 triangular layers) helical incommensurate arrangement is realized, due to the competition between the ferromagnetic interaction and the D-M interaction along the chain.Since the magnitude of spin on Cu 2+ is S = 1 2 , quantum fluctuations are important when one describes the magnetic behavior in the magnetic field . 12) Particularly, the magnetization process with a strong field often reveals quantum effects as macroscopic phenomena. Using quantum Monte Carlo calculations or spin wave theory, for the 2D triangular antiferromagnet (TAF) in the isotropic limit, it is predicted that the magnetization plateau appears at around one third of the saturation value M s . 13, 14) According to these predictions, when * Present address: Faculty of Education, Chiba University, 263-8522 Chiba, Japan.the external field H is applied parallel to the c-axis, 2D TAF undergoes a successive phase transition as shown in Fig. 1 (b) low-field coplanar, (c) collinear and (d) highfield coplanar structure in that order. In the field region where the magnetization plateau appears, the spin structure c...

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Fluctuation-induced phase in in a transverse magnetic field: experiment

Cited by 23 publications

References 18 publications

Magnetic field induced polar phase in the chiral magnetCsCuCl3

Magnetic field induced polar phase in the chiral magnetCsCuCl3

Electron Spin Resonance in Triangular Antiferromagnets

Oblique triangular antiferromagnetic phase inCsCu1−xCoxCl

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