Spin waves in a Bose Ferromagnet

Abstract

It is shown that the ferromagnetic transition takes place always above Bose-Einstein condensation in ferromagnetically coupled spinor Bose gases. We describe the Bose ferromagnet within Ginzburg-Landau theory by a "two-fluid" model below Bose-Einstein condensation. Both the Bose condensate and the normal phase are spontaneously magnetized. As a main result we show that spin waves in the two fluids are coupled together so as to produce only one mixed spin-wave mode in the coexisting state. The long wavelength spectrum is quadratic in the wave vector $\mathbf{k}$, consistent with usual ferromagnetism theory, and the spin-wave stiffness coefficient $c_s$ includes contributions from both the two phases, implying the "two-fluid" feature of the system. $c_s$ can show a sharp bend at the Bose-Einstein condensation temperature.

4 pages, 1 figure

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Cited by in corpus (20)

• Spinor Bose-Einstein condensates
• Precision measurement of spin-dependent interaction strengths for spin-1 and spin-2 87Rb atoms
• Coherent collisional spin dynamics in optical lattices
• Dipolar and spinor bosonic systems
• Domain-wall solutions of spinor Bose-Einstein condensates in an optical lattice
• Coherent dynamics of domain formation in the Bose Ferromagnet
• Polarization Signals of the 21 cm Background from the Era of Reionization
• Magnetic phase transitions of spin-1 ultracold bosons in a cubic optical lattice
• Static properties and spin dynamics of the ferromagnetic spin-1 Bose gas in magnetic field
• Thermodynamic properties of the itinerant-boson ferromagnet
• Enhancement of ferromagnetism by p-wave Cooper pairing in superconducting ferromagnets
• Renormalization group analysis of competition between distinct order parameters
• Quantum Interferometry with Microwave-dressed F=1 Spinor Bose-Einstein Condensates: Role of Initial States and Long Time Evolution
• Superfluidity and spin superfluidity in spinor Bose gases
• Magnetization relaxation and geometric forces in a Bose ferromagnet
• Spontaneous separation of two-component Fermi gases in a double-well trap
• Magnetic effects on the phase transitions in unconventional superconductors
• Reentrance of Bose-Einstein condensation in spinor atomic gases in magnetic field
• Phase-imprint induced domain formations and spin dynamics in spinor condensates
• Spin transport in coupled spinor Bose gases