On the Bloch Theorem Concerning Spontaneous Electric Current

Ōhashi, Y.; Momoi, Tsutomu

doi:10.1143/jpsj.65.3254

Cited by 52 publications

(53 citation statements)

References 19 publications

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“…This is a variant of Bloch's theorem that there is no net current flow in the ground state without external field. 57,58,59 We begin with defining the spin current. Since the Hamiltonian (1) conserves the z component of the total spin l s l , the s z current is a well-defined quantity.…”

Section: Triatic and Quartic Phasesmentioning

confidence: 99%

Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

et al. 2008

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We study the one-dimensional spin-1/2 Heisenberg chain with competing ferromagnetic nearestneighbor J1 and antiferromagnetic next-nearest-neighbor J2 exchange couplings in the presence of magnetic field. We use both numerical approaches (the density matrix renormalization group method and exact diagonalization) and effective field-theory approach, and obtain the ground-state phase diagram for wide parameter range of the coupling ratio J1/J2. The phase diagram is rich and has a variety of phases, including the vector chiral phase, the nematic phase, and other multipolar phases. In the vector chiral phase, which appears in relatively weak magnetic field, the ground state exhibits long-range order (LRO) of vector chirality which spontaneously breaks a parity symmetry. The nematic phase shows a quasi-LRO of antiferro-nematic spin correlation, and arises as a result of formation of two-magnon bound states in high magnetic fields. Similarly, the higher multipolar phases, such as triatic (p = 3) and quartic (p = 4) phases, are formed through binding of p magnons near the saturation fields, showing quasi-LRO of antiferro-multipolar spin correlations. The multipolar phases cross over to spin density wave phases as the magnetic field is decreased, before encountering a phase transition to the vector chiral phase at a lower field. The implications of our results to quasi-one-dimensional frustrated magnets (e.g., LiCuVO4) are discussed.

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Section: Triatic and Quartic Phasesmentioning

confidence: 99%

Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

et al. 2008

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“…The magnetic field is induced by the surface current and it is screened by the Meissner effect, so that the total current becomes zero. 42) Note that depending on the geometry of the sample these currents can generate a finite magnetization.…”

Section: Self-consistent Solutionmentioning

confidence: 99%

Quasiparticle States near the Surface and the Domain Wall in ap_x±ip_y-Wave Superconductor

1999

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The electronic states near a surface or a domain wall in the p-wave superconductor are studied for the order parameter of the form p x ±ip y -wave, which is a unitary odd-parity state with broken time-reversal symmetry. This state has been recently suggested as the superconducting state of Sr 2 RuO 4 . The spatial variation of the order parameter and vector potential is determined selfconsistently within the quasi-classical approximation. The local density of states at the surface is constant and does not show any peak-like or gap-like structure within the superconducting energy gap, in contrast to the case of the d-wave superconductors. The influence of an external magnetic field is mainly observable in the energy range above the bulk gap. On the other hand, there is a small energy gap in the local density of states at the domain wall between domains of the two degenerate p x +ip y -wave and p x −ip y -wave states.KEYWORDS: Sr2RuO4, p-wave superconductor, unitary state, time-reversal breaking state, boundary effect, surface, domain wall, quasi-classical theory, Ginzburg-Landau free energy §1. Introduction Sr 2 RuO 4 is the first superconductor with layered perovskite structure, which does not contain copper. 1) Although the structure is identical to that of some of the high-temperature superconductors, the transition temperature is rather low, T C =1.5K. There is a clear difference in the electronic structure, since Sr 2 RuO 4 is a good metal and even a Fermi liquid in its stoichiometric composition.Band structure calculations in good agreement with the de Haas-van Alphen measurements show that this compound has three Fermi surfaces originating from the three 4d-t 2g -orbitals of Ru 4+ . 2,3,4) There is growing experimental evidence that the superconducting state is unconventional (non-swave). Examples are the absence of a Hebel-Slichter peak in 1/T 1 T of NQR-measurements 5) and the sensitivity of T C on non-magnetic impurities. 6) It was suggested that the superconducting state has odd-parity (spin triplet) pairing. 7,8,10,9,11) There is a certain similarity with 3 He considering the correlation effects (superfluid 3 He has pwave pairing). 7) Furthermore, there is a series of related compounds such as SrRuO 3 which are 1 ferromagnetic suggesting that ferromagnetic spin fluctuations are probably enhanced in Sr 2 RuO 4 and mediate odd-parity, spin triplet pairing. 12,7,13) The recent discovery of intrinsic magnetism in the superconducting phase by µSR experiments indicates a pairing state with broken time reversal symmetry. 14) Symmetry considerations lead to the conclusion that this would only be possible for an odd-parity state. 15) A very strong support for odd-parity pairing comes also from the Knight shift data in the 17 O-NMR measurements which demonstrate the absence of any reduction of the spin susceptibility in the superconducting state. 16) The superconducting state compatible with all of these experiments is given by d(k)=ẑ(k x ±ik y ). 15) The presence of three electron bands forming the Fermi liqui...

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“…Note that no net current is present, i.e. the integrated current vanishes 24) , where L is the length of the system (L ≫ λ), and we have used eq. (4.5) .…”

Section: §1 Introductionmentioning

confidence: 99%

Time-Reversal Symmetry Breaking Surface States int-JModel

Kuboki

Sigrist

1998

J. Phys. Soc. Jpn.

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Recently a phenomenological Ginzburg-Landau (GL) theory has been proposed to describe the occurrence of a locally time-reversal symmetry (T ) breaking state near a Josephson junction between unconventional superconductors. In this paper we derive this type of GL free energy microscopically from the t − J model within a slave-boson mean-field approximation. The resulting GL free energy is shown to satisfy the conditions to have a T -violating surface state. The existence of this junction state may explain some of the recent experiments on High-Tc superconductors.

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On the Bloch Theorem Concerning Spontaneous Electric Current

Cited by 52 publications

References 19 publications

Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

Quasiparticle States near the Surface and the Domain Wall in ap_x±ip_y-Wave Superconductor

Time-Reversal Symmetry Breaking Surface States int-JModel

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On the Bloch Theorem Concerning Spontaneous Electric Current

Cited by 52 publications

References 19 publications

Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

Quasiparticle States near the Surface and the Domain Wall in apx±ipy-Wave Superconductor

Time-Reversal Symmetry Breaking Surface States int-JModel

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Product

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Quasiparticle States near the Surface and the Domain Wall in ap_x±ip_y-Wave Superconductor