Self-Trapping of Magnon Bose-Einstein Condensates in the Ground State and on Excited Levels: From Harmonic to Box Confinement

Autti, S.; Bunkov, Yu. M.; Eltsov, V. B.; Heikkinen, P. J.; Hosio, J. J.; Hunger, Pierre; Krusius, M.; Volovik, G. E.

doi:10.1103/physrevlett.108.145303

Cited by 52 publications

(87 citation statements)

References 25 publications

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“…Together F Z and F so form a three-dimensional trapping potential in which the magnon condensate is well isolated from the sample boundaries. A remarkable property of the textural trapping potential is that it can be modified by the precessing magnetization [13,18]. In this paper we, however, discuss condensates with a sufficiently small number of magnons, so that this self-modification of the trapping potential can be neglected.…”

Section: Methodsmentioning

confidence: 99%

“…[18,19]. The magnetic part of the trapping potential is provided by an additional pinch coil which creates a field in the opposite direction to 6 that of the main polarizing field.…”

Section: Methodsmentioning

confidence: 99%

“…Magnons from the excited levels relax towards the ground state, where spontaneously coherent precession of the magnetization M at a frequency ω 00 < ω rf emerges with an approximately common phase that is unrelated to that of the rf excitation field. This state is known as a Bose-Einstein condensate of magnons; the method of creating it by pumping magnons at higher frequencies is called off-resonant excitation [34,18]. Experimentally the off-resonant excitation is a convenient tool since separation of the excitation ω rf and detection ω 00 frequencies allows us to use the same coil for both purposes without interference.…”

Section: Magnon Bec Thermometrymentioning

confidence: 99%

“…When magnons with energies larger than the ground level in the trap are pumped into the system, for example by an rf pulse of suitable frequency and amplitude, they quickly relax to the ground state where a spontaneouslycoherent magnon BEC is formed [18]. The coherently precessing magnetization of the condensate induces a voltage in the pick-up coil.…”

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confidence: 99%

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Microkelvin Thermometry with Bose–Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid $$^3$$ 3 He

et al. 2014

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Coherent precession of trapped Bose-Einstein condensates of magnons is a sensitive probe for magnetic relaxation processes in superfluid 3 He-B down to the lowest achievable temperatures. We use the dependence of the relaxation rate on the density of thermal quasiparticles to implement thermometry in 3 He-B at temperatures below 300 µK. Unlike popular vibrating wire or quartz tuning fork based thermometers, magnon condensates allow for contactless temperature measurement and make possible an independent in situ determination of the residual zero-temperature relaxation provided by the radiation damping. We use this magnon-condensate-based thermometry to study the thermal impedance of the interface between A and B phases of superfluid 3 He. The magnon condensate is also a sensitive probe of the orbital order-parameter texture. This has allowed us to observe for the first time the non-thermal signature of the annihilation of two AB interfaces.

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Section: Methodsmentioning

confidence: 99%

“…[18,19]. The magnetic part of the trapping potential is provided by an additional pinch coil which creates a field in the opposite direction to 6 that of the main polarizing field.…”

Section: Methodsmentioning

confidence: 99%

Section: Magnon Bec Thermometrymentioning

confidence: 99%

mentioning

confidence: 99%

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Microkelvin Thermometry with Bose–Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid $$^3$$ 3 He

et al. 2014

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“…This "self-trapping" property has many interesting consequences [15,16]. In particular, it explains why the frequency of the precession in the condensate increases during relaxation.…”

Section: Introductionmentioning

confidence: 99%

Relaxation of Bose-Einstein Condensates of Magnons in Magneto-Textural Traps in Superfluid 3He-B

et al. 2013

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In superfluid3 He-B externally pumped quantized spin-wave excitations or magnons spontaneously form a Bose-Einstein condensate in a 3-dimensional trap created with the order-parameter texture and a shallow minimum in the polarizing field. The condensation is manifested by coherent precession of the magnetization with a common frequency in a large volume. The trap shape is controlled by the profile of the applied magnetic field and by the condensate itself via the spin-orbit interaction. The trapping potential can be experimentally determined with the spectroscopy of the magnon levels in the trap. We have measured the decay of the ground state condensates after switching off the pumping in the temperature range (0.14 ÷ 0.2)T c . Two contributions to the relaxation are identified: (1) spin diffusion with the diffusion coefficient proportional to the density of thermal quasiparticles and (2) the approximately temperature-independent radiation damping caused by the losses in the NMR pick-up circuit. The measured dependence of the relaxation on the shape of the trapping potential is in a good agreement with our calculations based on the magnetic field profile and the magnon-modified texture. Our values for the spin diffusion coefficient at low temperatures agree with the theoretical prediction and earlier measurements at temperatures above 0.5T c .

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Observation of Majorana Quasiparticles’ Edge States in Superfluid 3He

Bunkov

Gazizulin

2014

Appl Magn Reson

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We suggest in this article the nuclear magnetic resonance (NMR) method of observation and investigations of Majorana fermions at the edge of Topological Insulator, superfluid 3 He-B. The Majorana fermions form the remarkable quantum state of condensed matter where particle-like and antiparticle (holelike) excitations are indistinguishable. They have been observed recently by deviation of the temperature dependence of the superfluid 3 He-B heat capacity from the well-known exponential law for Bogoliubov quasiparticles at the world limit of ultra-low temperatures. The experimental data are well described by adding the heat capacity of Majorana quasiparticles' edge states with zero energy gap. We report here the results of the similar experiments with extended temperature range down to 125 lK. The possible way to detect these states by means of NMR is also discussed.

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Self-Trapping of Magnon Bose-Einstein Condensates in the Ground State and on Excited Levels: From Harmonic to Box Confinement

Cited by 52 publications

References 25 publications

Microkelvin Thermometry with Bose–Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid $$^3$$ 3 He

Microkelvin Thermometry with Bose–Einstein Condensates of Magnons and Applications to Studies of the AB Interface in Superfluid $$^3$$ 3 He

Relaxation of Bose-Einstein Condensates of Magnons in Magneto-Textural Traps in Superfluid 3He-B

Observation of Majorana Quasiparticles’ Edge States in Superfluid 3He

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