Stable Spin Precession at One Half of Equilibrium Magnetization in Superfluid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>He-<i>B</i>

Дмитриев, В. В.; Kosarev, I. B.; Krusius, M.; Ponarin, D. V.; Ruutu, V. M. H.; Volovik, G. E.

doi:10.1103/physrevlett.78.86

Cited by 63 publications

(15 citation statements)

References 12 publications

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“…They come from the spin-orbit interaction and are governed by the orbital vectorl. This allows us to regulate the profile of the GL energy: by applied counterflow 29 ; by deformation of aerogel 13,11 ; by exciting the precession at one half of equilibrium magnetization 14 ; by using flared-outl-texture 12 and topological defects; etc.…”

Section: Resultsmentioning

confidence: 99%

Bose-Einstein Condensation of Magnons in Superfluid 3He

Bunkov

Volovik

2007

J Low Temp Phys

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The possibility of Bose-Einstein condensation of excitations has been discussed for a long time. The phenomenon of the phase-coherent precession of magnetization in superfluid 3 He and the related effects of spin superfluidity are based on the true Bose-Einstein condensation of magnons. Several different states of coherent precession has been observed in 3 He-B: homogeneously precessing domain (HPD); persistent signal formed by Q-balls at very low temperatures; coherent precession with fractional magnetization; and two new modes of the coherent precession in compressed aerogel. In compressed aerogel the coherent precession has been also found in 3 He-A. Here we demonstrate that all these cases are examples of a Bose-Einstein condensation of magnons, with the magnon interaction term in the Gross-Pitaevskii equation being provided by different types of spin-orbit coupling in the background of the coherent precession.

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Section: Resultsmentioning

confidence: 99%

Bose-Einstein Condensation of Magnons in Superfluid 3He

Bunkov

Volovik

2007

J Low Temp Phys

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“…Several such modes are seen in 3 He-B: the homogeneously precessing domain (HPD) [6], the persistent induction signal, the PIS [2] considered here, and further modes near the transition temperature [7]. From recent work at Lancaster [1] and Grenoble [8] we can surmise The magnetic field gradient, acting both through the flow of spin supercurrent and the magnetic energy gradient, ensures that the precessing spin region is restricted to the low field end of the cell.…”

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confidence: 90%

Persistent Coherent Spin Precession in SuperfluidH3e−BDriven by Off-Resonant Excitation

et al. 1999

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In superfluid 3 He-B under conditions of negligible normal fluid density we are able to trap a domain of coherent spin precession away from the destructive influence of boundaries. After the domain is generated by an NMR pulse, the free spin precession may continue for several minutes. Remarkably, we find that these precessing domains may also be generated by cw excitation but only at a frequency considerably higher than that of the precession. We believe that this behavior may indicate that at our temperatures the precessing spin is able to stimulate the orbital moment into sympathetic precession.[S0031-9007 (99)09224-8] PACS numbers: 67.57.Lm, 67.57.Fg, 67.57.JjSuperfluid 3 He has a complex condensate with coherent ordering of the angular momenta and nuclear spins of the Cooper pairs. The coupled orbital and spin motions are both strongly damped by interaction with the normal fluid. Indeed, the orbital viscosity is so large that we can usually take the orbital moment as clamped and regard the condensate nuclear spin system as constituting an independent spin superfluid, the dynamics of which display a very complex range of behavior, readily probed by NMR. However, at the lowest temperatures where the orbital viscosity becomes negligible, there must also appear a similar range of behaviors associated with the orbital fluid. While spin precession is a general feature of magnetic materials, coupled coherent spin precession is a unique feature of the magnetic superfluids. The equivalent orbital motion has no analog in normal materials and is certain to yield as spectacular properties as has the spin superfluid. The search for such new phenomena provides a motive for cooling the superfluid to temperatures where we may be able to see the unfettered behavior of the condensate in all its aspects.With our present cell, we are able to cool the superfluid to temperatures low enough that domains of free coherent spin precession can persist for periods of many minutes [1]. These are the persistent induction signals (PIS) previously observed in 3 He-B at low temperatures [2][3][4][5]. Such domains form after a short NMR excitation pulse. After the pulse scrambles the spin and texture transiently in the experimental region, the long-lived precessional mode then appears as the superfluid attempts to relax to its previous state. In this paper we report that we can also excite these domains continuously by cw excitation. However, the behavior observed is entirely unique in NMR terms; the system responds with a domain precessing at a completely different frequency from that of the excitation. Since something more than just a simple spin fluid is responding here, we believe that these observations may provide the first evidence of orbital precession.The experiments are made in the double cell shown in Fig. 1. The liquid in the inner 5 mm diameter experimental volume can be cooled to 130 mK at zero bar. A steady magnetic field is applied vertically and a field gradient arranged such that the closed base of the cell is normally in l...

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“…Complete Bose-Einstein condensation of magnons in superfluid 3 He has been shown recently [2]. BECs of magnons are manifested macroscopically by the existence of various states of coherent spin precession that can be established spontaneously even in nonhomogeneous magnetic field [3][4][5]. These states exhibit all the properties of magnetic superfluidity: spin supercurrent, the Josephson effect, phase slippage, etc.…”

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confidence: 98%

New Non-Goldstone Collective Mode of BEC of Magnons in SuperfluidHe3−B

Človečko

Gažo²,

Kupka³

et al. 2008

Phys. Rev. Lett.

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Bose-Einstein condensation of magnons in superfluid 3He-B is experimentally manifested by various states where coherent spin precession is established spontaneously, even in nonhomogeneous magnetic fields. Once such a condensate with coherent spin precession is created, it occupies the state with minimal energy, the ground state. The application of an additional magnetic field to that condensate may cause its deflection from the energy minimum and the condensate responds by creating collective gapless oscillations known as Goldstone modes. This Letter reports the experimental observation of a new (non-)Goldstone mode, which can be viewed as an additional NMR mode of condensed magnons in a rotating frame of reference.

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Stable Spin Precession at One Half of Equilibrium Magnetization in Superfluid3He-B

Cited by 63 publications

References 12 publications

Bose-Einstein Condensation of Magnons in Superfluid 3He

Bose-Einstein Condensation of Magnons in Superfluid 3He

Persistent Coherent Spin Precession in SuperfluidH3e−BDriven by Off-Resonant Excitation

New Non-Goldstone Collective Mode of BEC of Magnons in SuperfluidHe3−B

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