scholarly journals Evidence for spin current driven Bose-Einstein condensation of magnons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Divinskiy ◽  
H. Merbouche ◽  
V. E. Demidov ◽  
K. O. Nikolaev ◽  
L. Soumah ◽  
...  
Keyword(s):  
Room Temperature ◽  
Chemical Potential ◽  
Spin Current ◽  
Einstein Condensation ◽  
Electronic Control ◽  
Spintronic Devices ◽  
Bose Einstein Condensation ◽  
Magnetic Insulators ◽  
Spatially Extended ◽  
Bose Einstein

AbstractThe quanta of magnetic excitations – magnons – are known for their unique ability to undergo Bose-Einstein condensation at room temperature. This fascinating phenomenon reveals itself as a spontaneous formation of a coherent state under the influence of incoherent stimuli. Spin currents have been predicted to offer electronic control of Bose-Einstein condensates, but this phenomenon has not been experimentally evidenced up to now. Here we show that current-driven Bose-Einstein condensation can be achieved in nanometer-thick films of magnetic insulators with tailored nonlinearities and minimized magnon interactions. We demonstrate that, above a certain threshold, magnons injected by the spin current overpopulate the lowest-energy level forming a highly coherent spatially extended state. We quantify the chemical potential of the driven magnon gas and show that, at the critical current, it reaches the energy of the lowest magnon level. Our results pave the way for implementation of integrated microscopic quantum magnonic and spintronic devices.

Bose–Einstein condensation of spin wave quanta at room temperature

2011 ◽  
Vol 369 (1951) ◽  
pp. 3575-3587 ◽  
Author(s):  
O. Dzyapko ◽  
V. E. Demidov ◽  
G. A. Melkov ◽  
S. O. Demokritov
Keyword(s):  
Room Temperature ◽  
Chemical Potential ◽  
Spin Waves ◽  
Einstein Condensation ◽  
Quasi Equilibrium ◽  
Magnetic Media ◽  
Bose Einstein Condensation ◽  
Garnet Films ◽  
Iron Garnet ◽  
Bose Einstein

Spin waves are delocalized excitations of magnetic media that mainly determine their magnetic dynamics and thermodynamics at temperatures far below the critical one. The quantum-mechanical counterparts of spin waves are magnons, which can be considered as a gas of weakly interacting bosonic quasi-particles. Here, we discuss the room-temperature kinetics and thermodynamics of the magnon gas in yttrium iron garnet films driven by parametric microwave pumping. We show that for high enough pumping powers, the thermalization of the driven gas results in a quasi-equilibrium state described by Bose–Einstein statistics with a non-zero chemical potential. Further increases of the pumping power cause a Bose–Einstein condensation documented by an observation of the magnon accumulation at the lowest energy level. Using the sensitivity of the Brillouin light scattering spectroscopy to the degree of coherence of the scattering magnons, we confirm the spontaneous emergence of coherence of the magnons accumulated at the bottom of the spectrum, occurring if their density exceeds a critical value.

scholarly journals Bose-Einstein Condensation of Confined Atomic Gases at Ultra Low Temperatures

2017 ◽  
Vol 9 (5) ◽  
pp. 96
Author(s):  
M. Serhan
Keyword(s):  
Low Temperatures ◽  
Chemical Potential ◽  
Scattering Length ◽  
Einstein Condensation ◽  
Pitaevskii Equation ◽  
Atomic Gases ◽  
Bose Einstein Condensation ◽  
Gaussian Type ◽  
Negative Scattering Length ◽  
Bose Einstein

In this work I solve the Gross-Pitaevskii equation describing an atomic gas confined in an isotropic harmonic trap by introducing a variational wavefunction of Gaussian type. The chemical potential of the system is calculated and the solutions are discussed in the weakly and strongly interacting regimes. For the attractive system with negative scattering length the maximum number of atoms that can be put in the condensate without collapse begins is calculated.

Bose–Einstein Condensation of Exciton-Polaritons in Organic Microcavities

2020 ◽  
Vol 71 (1) ◽  
pp. 435-459 ◽  
Author(s):  
Jonathan Keeling ◽  
Stéphane Kéna-Cohen
Keyword(s):  
Room Temperature ◽  
Organic Molecules ◽  
Einstein Condensation ◽  
Electronic Excitations ◽  
Optical Mode ◽  
Optical Cavities ◽  
Bose Einstein Condensation ◽  
Exciton Polaritons ◽  
Basic Physics ◽  
Bose Einstein

Bose–Einstein condensation describes the macroscopic occupation of a single-particle mode: the condensate. This state can in principle be realized for any particles obeying Bose–Einstein statistics; this includes hybrid light-matter excitations known as polaritons. Some of the unique optoelectronic properties of organic molecules make them especially well suited for the realization of polariton condensates. Exciton-polaritons form in optical cavities when electronic excitations couple collectively to the optical mode supported by the cavity. These polaritons obey bosonic statistics at moderate densities, are stable at room temperature, and have been observed to form a condensed or lasing state. Understanding the optimal conditions for polariton condensation requires careful modeling of the complex photophysics of organic molecules. In this article, we introduce the basic physics of exciton-polaritons and condensation and review experiments demonstrating polariton condensation in molecular materials.

scholarly journals Particle number fluctuations in a non-ideal pion gas

2018 ◽  
Vol 182 ◽  
pp. 02066
Author(s):  
Evgeni E. Kolomeitsev ◽  
Maxim E. Borisov ◽  
Dmitry N. Voskresensky
Keyword(s):  
Critical Point ◽  
Particle Number ◽  
Chemical Potential ◽  
Pion Mass ◽  
Thermodynamic Characteristics ◽  
Ideal Gas ◽  
Fixed Number ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein

We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the λφ4 interaction. The effective Lagrangian for the description of such a system is obtained by dropping the terms responsible for the change of the total particle number. Within the self-consistent Hartree approximation, we compute the effective pion mass, thermodynamic characteristics of the system and identify a critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. The normalized variance, skewness, and kurtosis of the particle number distributions are calculated. We demonstrate that all these characteristics remain finite at the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case.

Exciton-polariton Bose-Einstein condensation with a polymer at room temperature

2015 ◽  
Author(s):  
Thilo Stöferle ◽  
Johannes D. Plumhof ◽  
Lijian Mai ◽  
Ullrich Scherf ◽  
Rainer F. Mahrt
Keyword(s):  
Room Temperature ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein

Quantum statistics

Quantum 20/20 ◽  
2019 ◽  
pp. 37-54
Author(s):  
Ian R. Kenyon
Keyword(s):  
Chemical Potential ◽  
Quantum Statistics ◽  
Exclusion Principle ◽  
Einstein Condensation ◽  
Exchange Force ◽  
Stellar Objects ◽  
Bose Einstein Condensation ◽  
Boson Exchange ◽  
Degeneracy Pressure ◽  
Bose Einstein

Indistinguishability of like particles, and the fermion and boson exchange symmetries discussed.Pauli exclusion principle and features of multi-electron atoms, including selection rules are discussed. Degeneracy pressure and the formation of compact stellar objects is analysed. Quantum exchange force between electrons and its contribution to ferromagnetism is outlined. Fermi-Dirac and Bose-Einstein statistics, includng the chemical potential are derived. The conditions for Bose-Einstein condensation are deduced; condensates and their stability are considered.

scholarly journals Bose–Einstein condensation in magnetic insulators

2008 ◽  
Vol 4 (3) ◽  
pp. 198-204 ◽  
Author(s):  
Thierry Giamarchi ◽  
Christian Rüegg ◽  
Oleg Tchernyshyov
Keyword(s):  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Magnetic Insulators ◽  
Bose Einstein
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