Branching and resonant characteristics of surface plasma waves in a semi-bounded quantum plasma including spin-current effects

The dispersion relation for the waves propagating on the surface of a bounded quantum plasma with consideration of electron spin-current and ion-stream is derived and numerically investigated. We have found that one of the real parts of the wave frequency has the branching behavior beyond the instability domains. In such a region where the frequency branching occurs, the waves exhibit purely propagating mode. The resonant instability has also been investigated. We have found that when the phase velocity of the wave is close to the velocity of ion-stream the wave becomes unstable. However, the resonant growth rate is remarkably reduced by the effect of electron spin-current. The growth rate is also decreased by either the reduction of ion-stream velocity or the increase in quantum wavelength. Thus, the quantum effect in terms of the quantum wave number is found to suppress the resonant instability. It is also found that the increase in Fermi energy can reduce the growth rate of the resonant wave in the quantum plasma. Published by AIP Publishing.One of the authors (Y.-D.J.) gratefully acknowledges Dr. M. Rosenberg for useful discussions and warm hospitality while visiting the Department of Electrical and Computer Engineering at the University of California, San Diego. This research was initiated while one of the authors (Y.-D.J.) was affiliated with UC San Diego as a visiting professor. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (MISP) (Grant No. 2016R1A2B4011356)