Longitudinal NMR and spin states in the A-like phase of 3He in aerogel

Дмитриев, В. В.; Levitin, L. V.; Mulders, N.; Zmeev, D. E.

doi:10.1134/s0021364006200112

Cited by 19 publications

(52 citation statements)

References 13 publications

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“…82) NMR experiments have been performed on 3 He in 97.5% aerogel which support the view that the metastable A-like phase is in fact a robust state, 83) but other measurements 16,66) appear to have inconsistencies with this interpretation.…”

Section: Superfluidmentioning

confidence: 62%

“…In both cases the spectra are complex owing to a distribution of textures and, in the latter case, coexistence of these two phases in different parts of their aerogel sample. Direct observation of the longitudinal resonance frequency has also been reported by this group in both phases 66) as well as observation 67) of a homogeneous precession domain (HPD) in the aerogel B-phase. Sato et al 15) have observed HPD in an ESP-state of superfluid 3 He for the first time using aerogel.…”

Section: )mentioning

confidence: 92%

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Impurity Effects of Aerogel in Superfluid³He

et al. 2008

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The discovery of superfluid 3 He in high porosity silica aerogels, and subsequent experimental and theoretical work, have led to a better general understanding of quasiparticle scattering from impurities in unconventional pairing systems. It is immensely helpful for understanding impurity effects in the case of superfluid 3 He that the structure of its order parameter is well-established. An overview of impurity effects is presented with emphasis on those experiments which have a quantitative interpretation in terms of theoretical models for homogeneous and inhomogeneous scattering. The latter can account successfully for most experimental results.

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Section: Superfluidmentioning

confidence: 62%

Section: )mentioning

confidence: 92%

Impurity Effects of Aerogel in Superfluid³He

et al. 2008

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“…For example, in the bi-axial OG-SN state with l 2 z ≈ 1/3, and l 2 x = l 2 y for µ=0 one gets ∆ω ∝ (1 + cos β). Such dependence was observed in weakly anisotropic aerogel samples in [27,26,10].…”

Section: Two States Ofmentioning

confidence: 87%

“…Earlier it was found [26,22] that the A-like phase may exist in two states. One state is obtained if on cooling through T ca the low level of RF (or no RF) is used.…”

Section: Continuous Wave Nmr Experimentsmentioning

confidence: 99%

Orbital glass and spin glass states of 3He-A in aerogel

et al. 2010

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Glass states of superfluid A-like phase of 3 He in aerogel induced by random orientations of aerogel strands are investigated theoretically and experimentally. In anisotropic aerogel with stretching deformation two glass phases are observed. Both phases represent the anisotropic glass of the orbital ferromagnetic vectorl -the orbital glass (OG). The phases differ by the spin structure: the spin nematic vectord can be either in the ordered spin nematic (SN) state or in the disordered spin-glass (SG) state. The first phase (OG-SN) is formed under conventional cooling from normal 3 He. The second phase (OG-SG) is metastable, being obtained by cooling through the superfluid transition temperature, when large enough resonant continuous radio-frequency excitation are applied. NMR signature of different phases allows us to measure the parameter of the global anisotropy of the orbital glass induced by deformation.

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“…Previously the small negative frequency shift has been observed in some samples of aerogel [19,20], which can be explained by a residual deformations of these samples.…”

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confidence: 99%

Magnon BEC in superfluid 3He-A

Bunkov

Volovik²

2009

Jetp Lett.

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The new mode of magnetization precession in superfluid 3 He-A in a squeezed aerogel has been recently reported. We consider this mode in terms of the Bose-Einstein condensation (BEC) of magnons. The difference between magnon BEC states in 3 He-A and in 3 He-B is discussed. PACS:The discovery [1] and detailed investigations of the phase-coherent precession of magnetization in superfluid 3 He-B generated a search for similar phenomena in other systems. Superfluid 3 He-A could be a proper system. However, it was found that under typical conditions the coherent precession in 3 He-A is unstable [2] because of the convex shape of spin-orbit energy potential as function of magnetization [3,4]. It was suggested that the shape of potential can be inverted and thus the coherent precession can be stabilized if the orbital momentum of Cooper pairs in 3 He-A is oriented along the applied magnetic field [5]. Recently such orientation has been reached for 3 He-A immersed in the axially squeezed aerogel [6], and the first experiments with the coherently precessing state (CPS) of magnetization have been reported [7]. Here we discuss the phenomenon of the coherent precession of magnetization in superfluid 3 He-A in terms of the Bose-Einstein condensation (BEC) of magnons, and consider the difference between magnon BEC states in 3 He-A (CPS) and in 3 He-B (HPD). BEC is one of the most remarkable quantum phenomena. It corresponds to formation of collective quantum state, in which the macroscopic number of particles is governed by a single wave function. The formation of Bose-Einstein condensate was predicted by Einstein in 1925, for review see e.g. [8]. The almost perfect BEC state was observed in ultra could atomic gases. In Bose liquids, the BEC is strongly modified by interactions, but still remains the key mechanism for formation of coherent quantum state, which experiences the phenomenon of superfluidity: nondissipative superfluid current. In liquid 4 He the depletion of the condensate is very large: in the limit of zero temperature only about 10% of particles occupy the state with zero momentum. Nevertheless the whole liquid (100% of atoms) forms the 1) yuriy.bunkov@grenoble.cnrs.fr; volovik@boojum.hut.fi coherent quantum state at T = 0, so that the superfluid density equals the total density, ρ s (T = 0) = ρ. The latter is valid for any monoatomic superfluid system with translational invariance, including superfluid 3 He with the non BEC mechanism of coherent quantum state. If translational invariance is violated by impurities, crystal fields or other inhomogeneity, the superfluid component is suppressed:Superfluidity is a very general quantum property of matter at low temperatures, with variety of possible nondissipative superfluid currents, such as supercurrent of electric charge in superconductors; hypercharge supercurrent in the vacuum of Standard Model; supercurrent of color charge in a dense quark matter; etc. The origin of superfluidity is the spontaneous violation of the U (1) symmetry related to the conservation of ...

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Longitudinal NMR and spin states in the A-like phase of 3He in aerogel

Cited by 19 publications

References 13 publications

Impurity Effects of Aerogel in Superfluid³He

Impurity Effects of Aerogel in Superfluid³He

Orbital glass and spin glass states of 3He-A in aerogel

Magnon BEC in superfluid 3He-A

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Longitudinal NMR and spin states in the A-like phase of 3He in aerogel

Cited by 19 publications

References 13 publications

Impurity Effects of Aerogel in Superfluid3He

Impurity Effects of Aerogel in Superfluid3He

Orbital glass and spin glass states of 3He-A in aerogel

Magnon BEC in superfluid 3He-A

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Product

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Impurity Effects of Aerogel in Superfluid³He

Impurity Effects of Aerogel in Superfluid³He