Electronic Pumping of Quasiequilibrium Bose-Einstein Condensed Magnons
- Publisher: AMER PHYSICAL SOC
PHYSICAL REVIEW LETTERS
Condensed Matter - Mesoscale and Nanoscale Physics | Condensed Matter - Quantum Gases
arxiv: Condensed Matter::Quantum Gases | Condensed Matter::Strongly Correlated Electrons | Condensed Matter::Other
We theoretically investigate spin transfer between a system of quasiequilibrated Bose-Einstein-condensed magnons in an insulator in direct contact with a conductor. While charge transfer is prohibited across the interface, spin transport arises from the exchange coupling between insulator and conductor spins. In a normal insulator phase, spin transport is governed solely by the presence of thermal and spin-diffusive gradients; the presence of Bose-Einstein condensation (BEC), meanwhile, gives rise to a temperature-independent condensate spin current. Depending on the thermodynamic bias of the system, spin may flow in either direction across the interface, engendering the possibility of a dynamical phase transition of magnons. We discuss the experimental feasibility of observing a BEC steady state (fomented by a spin Seebeck effect), which is contrasted to the more familiar spin-transfer-induced classical instabilities.