Electron and magnon resonant tunneling: materials, physics and devices

Resonant tunneling (RT) originally refers to electron tunneling through the resonant states of double-barrier potentials with a series of sharply peaked transmission coefficients (close to unity) at certain energies. Electron RT can be used to design promising electronic devices such as RT diode. If the quantum well states are spin-dependent, the electron RT would exhibit spin-polarized or spin-selective properties, as observed in the double magnetic tunnel junctions with a thin intercalary ferromagnetic layer. As a result of the quantum wave-particle duality, RT can be further expanded to magnons-the quanta of spin waves, which opens up a new avenue of research-magnon RT. Because of the bosonic nature and macroscopic quantum coherence, the magnon RT may occur in a wide spectrum and temperature range (room temperature and above room temperature), while the electron RT typically occurs around the Fermi level and at low temperature or around room temperature. Here, we review the recent advances in RT physics of electron and magnon, and outline possible device implications.