Physical Review Letters

Order-parameter textures and boundary conditions in rotating vortex-free B3

J. S. Korhonen, A. D. Gongadze, Z. Janú, Y. Kondo, M. Krusius, Yu. M. Mukharsky, E. V. Thuneberg

Published Sep 3, 1990• 30 citations

Abstract

The order-parameter texture has been studied in rotating $^{3}\mathit{B}$ in the vortex-free state with NMR techniques. A sequence of textural phase transitions is observed with increasing rotation speed. It is generated by competing interactions with magnetic field, surfaces, and rotation. Two surface interactions are extracted: the susceptibility anisotropy at the wall and the gyromagnetism due to a magnetic-field-induced surface supercurrent. The results are consistent with an order-parameter structure approaching the planar state with diffuse quasiparticle scattering at the wall.

DOI: 10.1103/physrevlett.65.1211

Related papers

Vortex-free state of 3 He-B in a rotating cylinder

Pertti Juhani Hakonen, Kaj K. Nummila

Physical Review LettersAug 31, 198770 citations

Order parameter and exchange field of superfluid B3 near magnetically active surfaces

Weiyi Zhang

Physical review. B, Condensed matterJun 1, 19940 citations

Homogeneous spin precession in rotating vortex-free He3 -B: Measurement of the superfluid density anisotropy

J. S. Korhonen, Yu. M. Bunkov, Vladimir V. Dmitriev +5 more

Physical review. B, Condensed matterDec 1, 199216 citations

Coreless and singular vortex lattices in rotating spinor Bose-Einstein condensates

Takeshi Mizushima, Naoko Kobayashi, Kazushige Machida

arXiv:cond-mat/0407684Physical Review AOct 12, 200492 citations

Investigation of spin supercurrents in B3

A. S. Borovik‐Romanov, Yu. M. Bunkov, Vladimir V. Dmitriev +2 more

Physical Review LettersApr 3, 1989126 citations

Two different vortex states in rotating A3 observed by use of negative ions

Juha Simola, L. Skrbek, Kaj K. Nummila +1 more

Physical Review LettersMar 2, 198788 citations

Physical Review Letters

Order-parameter textures and boundary conditions in rotating vortex-free B3

J. S. Korhonen, A. D. Gongadze, Z. Janú, Y. Kondo, M. Krusius, Yu. M. Mukharsky, E. V. Thuneberg

Published Sep 3, 1990• 30 citations

Publisher

Abstract

The order-parameter texture has been studied in rotating

^{3}\mathit{B}

in the vortex-free state with NMR techniques. A sequence of textural phase transitions is observed with increasing rotation speed. It is generated by competing interactions with magnetic field, surfaces, and rotation. Two surface interactions are extracted: the susceptibility anisotropy at the wall and the gyromagnetism due to a magnetic-field-induced surface supercurrent. The results are consistent with an order-parameter structure approaching the planar state with diffuse quasiparticle scattering at the wall.

DOI: 10.1103/physrevlett.65.1211

Related papers

Vortex-free state of 3 He-B in a rotating cylinder

Pertti Juhani Hakonen, Kaj K. Nummila

Vortex-free states have been observed in $^{3}\mathit{B}$ at rotation speeds up to 0.9 rad/s in a cylinder of 5-mm diameter. The measured cw NMR spectra, reflecting the order-parameter structure, respond very differently to rotation in opposite directions. The sign of this asymmetry is not linked to the direction of the applied magnetic field, as expected for a gyromagnetic effect, but varies randomly from one cooldown to another.Vortex-free states have been observed in $^{3}\mathit{B}$ at rotation speeds up to 0.9 rad/s in a cylinder of 5-mm diameter. The measured cw NMR spectra, reflecting the order-parameter structure, respond very differently to rotation in opposite directions. The sign of this asymmetry is not linked to the direction of the applied magnetic field, as expected for a gyromagnetic effect, but varies randomly from one cooldown to another.

Physical Review LettersAug 31, 198770 citations

Order parameter and exchange field of superfluid B3 near magnetically active surfaces

Weiyi Zhang

The order parameter and exchange field of superfluid $^{3}\mathit{B}$ near magnetically active surfaces with perfect reflection are calculated using the quasiclassical theory and a magnetically scattering surface model. Our results show that an exchange field is usually induced in the vicinity of such surfaces due to the spin rotation of the impending quasiparticles, but for certain magnetic configuration of the surface, the order parameters are not depressed at all. This is in strong contrast to the situation near nonmagnetic surfaces where the perpendicular order parameter always vanishes due to the triplet pairing nature of the Cooper pair. We discuss the possible application of this property to identify the Cooper pair symmetry of other unconventional superconductors.The order parameter and exchange field of superfluid $^{3}\mathit{B}$ near magnetically active surfaces with perfect reflection are calculated using the quasiclassical theory and a magnetically scattering surface model. Our results show that an exchange field is usually induced in the vicinity of such surfaces due to the spin rotation of the impending quasiparticles, but for certain magnetic configuration of the surface, the order parameters are not depressed at all. This is in strong contrast to the situation near nonmagnetic surfaces where the perpendicular order parameter always vanishes due to the triplet pairing nature of the Cooper pair. We discuss the possible application of this property to identify the Cooper pair symmetry of other unconventional superconductors.

Physical review. B, Condensed matterJun 1, 19940 citations

Homogeneous spin precession in rotating vortex-free He3 -B: Measurement of the superfluid density anisotropy

J. S. Korhonen, Yu. M. Bunkov, Vladimir V. Dmitriev +5 more

In transverse NMR at high rf excitation, it is possible to separate a $^{3}\mathit{B}$ sample into two magnetic domains. In one domain the spins are precessing coherently with a large tilting angle in relation to the polarizing magnetic field while in the other they are stationary and oriented parallel to the field. We have studied the two-domain system during vortex-free rotation and found that the boundary region between the precessing and static domains is sensitive to superfluid counterflow, flowing parallel to the boundary. The volume of the precessing domain decreases and the NMR absorption, associated with spin diffusion across the boundary, increases. The shift of the domain boundary is analyzed in terms of the competition between the kinetic energy of counterflow and the gradient in the Zeeman energy. From the shift we obtain the superfluid density anisotropy, induced by the magnetic field. A calculation in the weak-coupling approximation explains only half of the measured ansiotropy at low pressures. At high pressures the discrepancy is smaller.In transverse NMR at high rf excitation, it is possible to separate a $^{3}\mathit{B}$ sample into two magnetic domains. In one domain the spins are precessing coherently with a large tilting angle in relation to the polarizing magnetic field while in the other they are stationary and oriented parallel to the field. We have studied the two-domain system during vortex-free rotation and found that the boundary region between the precessing and static domains is sensitive to superfluid counterflow, flowing parallel to the boundary. The volume of the precessing domain decreases and the NMR absorption, associated with spin diffusion across the boundary, increases. The shift of the domain boundary is analyzed in terms of the competition between the kinetic energy of counterflow and the gradient in the Zeeman energy. From the shift we obtain the superfluid density anisotropy, induced by the magnetic field. A calculation in the weak-coupling approximation explains only half of the measured ansiotropy at low pressures. At high pressures the discrepancy is smaller.

Physical review. B, Condensed matterDec 1, 199216 citations

Coreless and singular vortex lattices in rotating spinor Bose-Einstein condensates

Takeshi Mizushima, Naoko Kobayashi, Kazushige Machida

We theoretically investigate vortex-lattice phases of rotating spinor Bose-Einstein condensates (BEC's) with a ferromagnetic spin interaction by numerically solving the Gross-Pitaevskii equation. The spinor BEC under slow rotation can sustain a rich variety of exotic vortices due to the multicomponent order parameters, such as Mermin-Ho and Anderson-Toulouse coreless vortices (the two-dimensional Skyrmion and meron) and nonaxisymmetric vortices with shifting vortex cores. Here, we present the spin texture of various vortex-lattice states at higher rotation rates and in the presence of an external magnetic field. In addition, the vortex phase diagram is constructed in the plane of the total magnetization $M$ and the external rotation frequency $\ensuremath{\Omega}$ by comparing the free energies of possible vortices. It is shown that the vortex phase diagrams in the $M\text{\ensuremath{-}}\ensuremath{\Omega}$ plane may be divided into two categories: (i) the coreless vortex lattice formed by the several types of Mermin-Ho vortices and (ii) the vortex lattice filling in the cores with the pure polar (antiferromagnetic) state. In particular, it is found that the type-(ii) state forms composite lattices of coreless and polar-core vortices. The difference between type (i) and type (ii) results from the existence of the singularity of the spin textures, which may be experimentally confirmed by the spin imaging within polarized light recently proposed by Carusotto and Mueller. We also discuss the stability of triangular and square lattice states for rapidly rotating condensates.We theoretically investigate vortex-lattice phases of rotating spinor Bose-Einstein condensates (BEC's) with a ferromagnetic spin interaction by numerically solving the Gross-Pitaevskii equation. The spinor BEC under slow rotation can sustain a rich variety of exotic vortices due to the multicomponent order parameters, such as Mermin-Ho and Anderson-Toulouse coreless vortices (the two-dimensional Skyrmion and meron) and nonaxisymmetric vortices with shifting vortex cores. Here, we present the spin texture of various vortex-lattice states at higher rotation rates and in the presence of an external magnetic field. In addition, the vortex phase diagram is constructed in the plane of the total magnetization $M$ and the external rotation frequency $\ensuremath{\Omega}$ by comparing the free energies of possible vortices. It is shown that the vortex phase diagrams in the $M\text{\ensuremath{-}}\ensuremath{\Omega}$ plane may be divided into two categories: (i) the coreless vortex lattice formed by the several types of Mermin-Ho vortices and (ii) the vortex lattice filling in the cores with the pure polar (antiferromagnetic) state. In particular, it is found that the type-(ii) state forms composite lattices of coreless and polar-core vortices. The difference between type (i) and type (ii) results from the existence of the singularity of the spin textures, which may be experimentally confirmed by the spin imaging within polarized light recently proposed by Carusotto and Mueller. We also discuss the stability of triangular and square lattice states for rapidly rotating condensates.

arXiv:cond-mat/0407684Physical Review AOct 12, 200492 citations

Investigation of spin supercurrents in B3

A. S. Borovik‐Romanov, Yu. M. Bunkov, Vladimir V. Dmitriev +2 more

Magnetic supercurrents are observed in superfluid $^{3}\mathit{B}$ . These supercurrents transport the longitudinal magnetization from one experimental cell to another through a narrow channel, driven by gradients of the order parameter. In both cells NMR is induced by separate signal generators at the same frequency. The supercurrent arises if a phase difference of the magnetization precession is established across the narrow channel. A critical spin supercurrent is measured at which precession phase slippage takes place. Experimental values of the critical spin supercurrent are in agreement with theoretical predictions.Magnetic supercurrents are observed in superfluid $^{3}\mathit{B}$. These supercurrents transport the longitudinal magnetization from one experimental cell to another through a narrow channel, driven by gradients of the order parameter. In both cells NMR is induced by separate signal generators at the same frequency. The supercurrent arises if a phase difference of the magnetization precession is established across the narrow channel. A critical spin supercurrent is measured at which precession phase slippage takes place. Experimental values of the critical spin supercurrent are in agreement with theoretical predictions.

Physical Review LettersApr 3, 1989126 citations

Two different vortex states in rotating A3 observed by use of negative ions

Juha Simola, L. Skrbek, Kaj K. Nummila +1 more

First experiments suggesting the presence of singular vortices in rotating $^{3}\mathit{A}$ are reported. Our studies on the interaction between negative ions and vortex textures verify the existence of the continuous vortices seen earlier by NMR, but evidence for a new vortex state with high ion mobility along the core is also found. The nucleation of the new vortex depends on the external magnetic field and the rotation history of the sample.First experiments suggesting the presence of singular vortices in rotating $^{3}\mathit{A}$ are reported. Our studies on the interaction between negative ions and vortex textures verify the existence of the continuous vortices seen earlier by NMR, but evidence for a new vortex state with high ion mobility along the core is also found. The nucleation of the new vortex depends on the external magnetic field and the rotation history of the sample.

Physical Review LettersMar 2, 198788 citations

The order-parameter texture has been studied in rotating

^{3}\mathit{B}

Vortex-free states have been observed in

^{3}\mathit{B}

at rotation speeds up to 0.9 rad/s in a cylinder of 5-mm diameter. The measured cw NMR spectra, reflecting the order-parameter structure, respond very differently to rotation in opposite directions. The sign of this asymmetry is not linked to the direction of the applied magnetic field, as expected for a gyromagnetic effect, but varies randomly from one cooldown to another.

The order parameter and exchange field of superfluid

^{3}\mathit{B}

near magnetically active surfaces with perfect reflection are calculated using the quasiclassical theory and a magnetically scattering surface model. Our results show that an exchange field is usually induced in the vicinity of such surfaces due to the spin rotation of the impending quasiparticles, but for certain magnetic configuration of the surface, the order parameters are not depressed at all. This is in strong contrast to the situation near nonmagnetic surfaces where the perpendicular order parameter always vanishes due to the triplet pairing nature of the Cooper pair. We discuss the possible application of this property to identify the Cooper pair symmetry of other unconventional superconductors.

In transverse NMR at high rf excitation, it is possible to separate a

^{3}\mathit{B}

sample into two magnetic domains. In one domain the spins are precessing coherently with a large tilting angle in relation to the polarizing magnetic field while in the other they are stationary and oriented parallel to the field. We have studied the two-domain system during vortex-free rotation and found that the boundary region between the precessing and static domains is sensitive to superfluid counterflow, flowing parallel to the boundary. The volume of the precessing domain decreases and the NMR absorption, associated with spin diffusion across the boundary, increases. The shift of the domain boundary is analyzed in terms of the competition between the kinetic energy of counterflow and the gradient in the Zeeman energy. From the shift we obtain the superfluid density anisotropy, induced by the magnetic field. A calculation in the weak-coupling approximation explains only half of the measured ansiotropy at low pressures. At high pressures the discrepancy is smaller.

M

and the external rotation frequency $\ensuremath{\Omega}$ by comparing the free energies of possible vortices. It is shown that the vortex phase diagrams in the $M\text{\ensuremath{-}}\ensuremath{\Omega}$ plane may be divided into two categories: (i) the coreless vortex lattice formed by the several types of Mermin-Ho vortices and (ii) the vortex lattice filling in the cores with the pure polar (antiferromagnetic) state. In particular, it is found that the type-(ii) state forms composite lattices of coreless and polar-core vortices. The difference between type (i) and type (ii) results from the existence of the singularity of the spin textures, which may be experimentally confirmed by the spin imaging within polarized light recently proposed by Carusotto and Mueller. We also discuss the stability of triangular and square lattice states for rapidly rotating condensates.

Magnetic supercurrents are observed in superfluid

^{3}\mathit{B}

. These supercurrents transport the longitudinal magnetization from one experimental cell to another through a narrow channel, driven by gradients of the order parameter. In both cells NMR is induced by separate signal generators at the same frequency. The supercurrent arises if a phase difference of the magnetization precession is established across the narrow channel. A critical spin supercurrent is measured at which precession phase slippage takes place. Experimental values of the critical spin supercurrent are in agreement with theoretical predictions.

First experiments suggesting the presence of singular vortices in rotating

^{3}\mathit{A}

are reported. Our studies on the interaction between negative ions and vortex textures verify the existence of the continuous vortices seen earlier by NMR, but evidence for a new vortex state with high ion mobility along the core is also found. The nucleation of the new vortex depends on the external magnetic field and the rotation history of the sample.