Dynamics of a Bose-Einstein condensate of excited magnons

Vannucchi, Fabio Stucchi; Vasconcellos, Áurea R.; Luzzi, Roberto

doi:10.1140/epjb/e2013-40172-6

Cited by 6 publications

(15 citation statements)

References 60 publications

(143 reference statements)

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“…As fully described elsewhere, the theory confirms that the phenomenon consists of an NEFBEC. Resorting to a two‐fluid model, numerical results can be obtained, which are displayed in Figure (the evolution of the mean population in the condensate and in the “normal” state) and (the mean population in the condensate and that in the “normal” state in the steady‐state).…”

Section: Several Particular Cases Of Nebecsupporting

confidence: 80%

“…In other words, the energy pumped into the system instead of being redistributed among the magnons in such non‐thermal conditions is transferred to the mode that is lowest in frequency (with a fraction of course being dissipated to the surrounding media). Such a phenomenon has been referred to as a non‐equilibrium Bose–Einstein condensation, and we have shown it to be an additional case of NEBEC …”

Section: Several Particular Cases Of Nebecmentioning

confidence: 72%

“…As already noted, the complete details are given in refs. [], and a complete study of the irreversible thermodynamics of the NEFBEC of magnons is under way …”

Section: Several Particular Cases Of Nebecmentioning

confidence: 99%

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Non‐Equilibrium Bose–Einstein‐Like Condensation

2018

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The original Bose–Einstein condensation (BEC) was theoretically established in the 1920s, for the case of an ideal gas of boson particles (a consequence of the symmetry of the wave function). In the 1990s, it was realized in systems of atomic alkali gases. At the beginning of the 21st century, investigators considered its emergence in solid‐state matter, and a BEC‐like phenomenon was observed in the case of bosonic quasiparticles (elementary excitations in solids). Both types of BEC can occur in a condensation in conditions of thermodynamic equilibrium. A third type of what has been dubbed a BEC in non‐equilibrium conditions can occur in systems of bosonic quasiparticles (phonons, magnons, excitons); this phenomenon (which can be considered as cases of systems with complex behavior) follows after a certain threshold of intensity of an external pumping source is achieved. In this review, after brief comments on the two types of BEC in equilibrium, a description is presented on how a BEC‐like phenomenon arises in systems of quasiparticles that are driven away from thermodynamic equilibrium, and several examples are described. This description is given within a unique theoretical framework, and a comparison with experimental results is performed; in addition, the possible technological applications are outlined.

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Section: Several Particular Cases Of Nebecsupporting

confidence: 80%

Section: Several Particular Cases Of Nebecmentioning

confidence: 72%

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Non‐Equilibrium Bose–Einstein‐Like Condensation

2018

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“…A fourth one is the case of magnons already referred to [3,4], which we here analyze in depth. The thermal bath is constituted by the phonon system, with which a nonlinear interaction exists, and the magnons are driven arbitrarily out of equilibrium by a source of electromagnetic radio frequency [23,24]. Technological applications are related to the construction of sources of coherent microwave radiation [25,26].…”

mentioning

confidence: 99%

Statistical thermodynamics of the Fröhlich-Bose-Einstein condensation of magnons out of equilibrium

Vannucchi

Luzzi

2019

Phys. Rev. E

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A non-equilibrium statistical-thermodynamic approach to the study of a Fröhlich-Bose-Einstein condensation of magnons under radio-frequency radiation pumping is presented. Such a system displays a complex behavior consisting in steady-state conditions to the emergence of a synergetic dissipative structure resembling the Bose-Einstein condensation of systems in equilibium. A kind of "two fluid model" arises: the "normal" non-equilibrium structure and Fröhlich condensate or "nonequilibrium" one, which is shown to be an attractor to the system. We analyze some aspects of the irreversible thermodynamics of this dissipative complex system, namely, its informational entropy, expressions for the fluctuations in non-equilibrium conditions, the associated Maxwell relations and the formulation of a generalized H -theorem. We also study the informational entropy production of the system, an order parameter is introduced and Glansdorff-Prigogine criteria for evolution and (in)stability are verified. * fs.vannucchi@unesp.br

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“…4 shows the results obtained by numerically solving Eq. (28). Based on them, we summarize the qualitative distinction between the magnon currents in the C-P junction and those in the C-C junction 7 .…”

mentioning

confidence: 99%

Magnon transport through microwave pumping

2015

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We present a microscopic theory of magnon transport in ferromagnetic insulators (FIs). Using magnon injection through microwave pumping, we propose a way to generate magnon dc currents and show how to enhance their amplitudes in hybrid ferromagnetic insulating junctions. To this end focusing on a single FI, we first revisit microwave pumping at finite (room) temperature from the microscopic viewpoint of magnon injection. Next, we apply it to two kinds of hybrid ferromagnetic insulating junctions. The first is the junction between a quasi-equilibrium magnon condensate and magnons being pumped by microwave, while the second is the junction between such pumped magnons and noncondensed magnons. We show that quasi-equilibrium magnon condensates generate ac and dc magnon currents, while noncondensed magnons produce essentially a dc magnon current. The ferromagnetic resonance (FMR) drastically increases the density of the pumped magnons and enhances such magnon currents. Lastly, using microwave pumping in a single FI, we discuss the possibility that a magnon current through an Aharonov-Casher phase flows persistently even at finite temperature. We show that such a magnon current arises even at finite temperature in the presence of magnon-magnon interactions. Due to FMR, its amplitude becomes much larger than the condensed magnon current.

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Dynamics of a Bose-Einstein condensate of excited magnons

Cited by 6 publications

References 60 publications

Non‐Equilibrium Bose–Einstein‐Like Condensation

Non‐Equilibrium Bose–Einstein‐Like Condensation

Statistical thermodynamics of the Fröhlich-Bose-Einstein condensation of magnons out of equilibrium

Magnon transport through microwave pumping

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