Class H insulation system for railway traction motor

Kawamura, Yukinori; Minami, Makiko; Matsushita, Yoshinao; Haga, K.; Nomura, Naofumi

doi:10.1109/eeic.1983.7465095

Cited by 5 publications

(12 citation statements)

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“…Spiral phases carry not only a magnetic order parameter, but also a chiral order parameter. In particular, a vector chirality can be defined on an upwards pointing triangle with counter-clockwise labeled corners (i, j, k) as [45]…”

Section: Spin and Chirality Correlations From Msw Theorymentioning

confidence: 99%

Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ₁J₂J₃model with Heisenberg interactions

et al. 2011

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We study the ground state phases of the S = 1/2 Heisenberg quantum antiferromagnet on the spatially anisotropic triangular lattice and on the square lattice with up to next-next-nearest neighbor coupling (the J 1 J 2 J 3 model), making use of Takahashi's modified spin-wave (MSW) theory supplemented by ordering vector optimization. We compare the MSW results with exact diagonalization and projectedentangled-pair-states calculations, demonstrating their qualitative and quantitative reliability. We find that MSW theory correctly accounts for strong quantum effects on the ordering vector of the magnetic phases of the models under investigation: in particular collinear magnetic order is promoted at the expenses of non-collinear (spiral) order, and several spiral states which are stable at the classical level, disappear from the quantum phase diagram. Moreover, collinear states and non-collinear ones are never connected continuously, but they are separated by parameter regions in which MSW breaks down, signaling the possible appearance of a non-magnetic ground state.In the case of the spatially anisotropic triangular lattice, a large breakdown region appears also for weak couplings between the chains composing the lattice, suggesting the possible occurrence of a large non-magnetic region continuously connected with arXiv:1012.4491v1 [cond-mat.str-el] 20 Dec 2010 the spin-liquid state of the uncoupled chains.

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Section: Spin and Chirality Correlations From Msw Theorymentioning

confidence: 99%

Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ₁J₂J₃model with Heisenberg interactions

et al. 2011

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“…Spiral phases carry not only a magnetic order parameter, but also a chiral order parameter. In particular, a vector chirality [27] can be defined on an upwards pointing triangle with counter-clockwise labeled corners (i, j, k) as κ ∆ = 2 0 0.5 and on a downwards pointing triangle with counter-clockwise labeled corners (i, l, j) as κ ∇ =…”

Section: B Ordering Vector Spin-spin and Chiral Correlationsmentioning

confidence: 99%

Modified spin-wave theory with ordering vector optimization: frustrated bosons on the spatially anisotropic triangular lattice

Hauke¹,

Roscilde²,

Murg³

et al. 2010

New J. Phys.

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We investigate a system of frustrated hardcore bosons, modeled by an XY antiferromagnet on the spatially anisotropic triangular lattice, using Takahashi's modified spin-wave (MSW) theory. In particular we implement ordering vector optimization on the ordered reference state of MSW theory, which leads to significant improvement of the theory and accounts for quantum corrections to the classically ordered state. The MSW results at zero temperature compare favorably to exact diagonalization (ED) and projected entangled-pair state (PEPS) calculations. The resulting zero-temperature phase diagram includes a 1D quasi-ordered phase, a 2D Néel ordered phase, and a 2D spiraling ordered phase. Strong indications coming from the ED and PEPS calculations, as well as from the breakdown of MSW theory, suggest that the various ordered or quasi-ordered phases are separated by spin-liquid phases with short-range correlations, in analogy to what has been predicted for the Heisenberg model on the same lattice. Within MSW theory we also explore the finite-temperature phase diagram. In agreement with Berezinskii-Kosterlitz-Thouless (BKT) theory, we find that zero-temperature long-range-ordered phases turn into quasi-ordered phases (up to a BKT transition temperature), while zero-temperature quasi-ordered phases become shortrange correlated at finite temperature. These results show that, despite its simplicity, modified spin-wave theory is very well suited for describing ordered and quasi-ordered phases of frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at zero and finite temperatures. While MSW theory, just as other theoretical methods, cannot describe spin-liquid phases, its breakdown provides a fast and reliable method for singling out Hamiltonians which may feature these intriguing quantum phases. We thus suggest a tool for guiding our search for interesting systems whose properties are necessarily studied with a physical quantum simulator instead of theoretical methods.

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“…It has subsequently been suggested that, in the ordering of the 3D Heisenberg SG, the chirality was "decoupled" from the spin, the chiral-glass (CG) order taking place at a temperature higher than the SG order, i.e., T CG > T SG [17,18,19,20,21]. Based on such a spin-chirality decoupling picture of the 3D isotropic Heisenberg SG, a chirality scenario of experimental SG transition was proposed [16,20,21,22]: According to this scenario, the chirality is a hidden order parameter of SG transition. Real SG transition of weakly anisotropic SG magnets is then a "disguised" CG transition, where the chirality is mixed into the spin sector via a weak random magnetic anisotropy.…”

Section: Introductionmentioning

confidence: 99%

“…For a recent review, the reader is referred to Ref. [21] The chirality scenario is capable of explaining several long-standing puzzles concerning the experimental SG transition [1] in a natural way, such as the origin of the non-Ising critical exponents observed in canonical SGs [20,21], the apparent absence of the Heisenberg-to-Ising crossover in the measured nonlinear susceptibility [20,21], and the origin of the mean-field-like transition lines (the so-called AT and GT lines) often observed experimentally in the SG phase diagram in magnetic fields [20,21,23,24,25]. The chirality scenario remains to be an attractive hypothesis in consistently explaining various experimental observations for canonical SGs, and hence, it is an important task to examine the validity of the basic assumption underlying this scenario, i.e., the occurrence of the spin-chirality decoupling in the 3D isotropic Heisenberg SG.…”

Section: Introductionmentioning

confidence: 99%

“…In recent numerical studies of the 3D Heisenberg EA model, consensus now seems to appear that the 3D Heisenberg SG indeed exhibits a finite-temperature transition [16,17,18,19,20,21,22,26,27,28,29,30,31,32,33,34,35,36]. However, the nature of the transition, especially whether the model really exhibits the spin-chirality decoupling, is still under hot debate [27,28,29,30,32,33,34,35,36].…”

Section: Introductionmentioning

confidence: 99%

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Monte Carlo studies of chiral and spin ordering of the three-dimensional Heisenberg spin glass

Viet

Kawamura

2009

Phys. Rev. B

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The nature of the ordering of the three-dimensional isotropic Heisenberg spin glass with nearest-neighbor random Gaussian coupling is studied by extensive Monte Carlo simulations. Several independent physical quantities are measured both for the spin and for the chirality, including the correlation-length ratio, the Binder ratio, the glass order parameter, the overlap distribution function, and the nonself-averageness parameter. By controlling the effect of the correction-to-scaling, we have obtained a numerical evidence for the occurrence of successive chiral-glass and spin-glass transitions at nonzero temperatures, T CG Ͼ T SG Ͼ 0. Hence, the spin and the chirality are decoupled in the ordering of the model. The chiral-glass exponents are estimated to be CG = 1.4Ϯ 0.2 and CG = 0.6Ϯ 0.2, indicating that the chiral-glass transition lies in a universality class different from that of the Ising spin glass. The possibility that the spin and chiral sectors undergo a simultaneous Kosterlitz-Thouless-type transition is ruled out. The chiral-glass state turns out to be nonself-averaging, possibly accompanying a one-step-like peculiar replica-symmetry breaking. Implications to the chirality scenario of experimental spin-glass transitions are discussed.

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Class H insulation system for railway traction motor

Cited by 5 publications

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Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ₁J₂J₃model with Heisenberg interactions

Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ₁J₂J₃model with Heisenberg interactions

Modified spin-wave theory with ordering vector optimization: frustrated bosons on the spatially anisotropic triangular lattice

Monte Carlo studies of chiral and spin ordering of the three-dimensional Heisenberg spin glass

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Class H insulation system for railway traction motor

Cited by 5 publications

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Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ1J2J3model with Heisenberg interactions

Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ1J2J3model with Heisenberg interactions

Modified spin-wave theory with ordering vector optimization: frustrated bosons on the spatially anisotropic triangular lattice

Monte Carlo studies of chiral and spin ordering of the three-dimensional Heisenberg spin glass

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Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ₁J₂J₃model with Heisenberg interactions

Modified spin-wave theory with ordering vector optimization: spatially anisotropic triangular lattice andJ₁J₂J₃model with Heisenberg interactions