Oblique propagation of longitudinal waves in magnetized spin-1/2 plasmas: Independent evolution of spin-up and spin-down electrons

TL;DR

This paper investigates how separate spin-up and spin-down electron dynamics in magnetized quantum plasmas lead to four distinct longitudinal wave solutions, expanding understanding beyond traditional two-wave models.

Contribution

It introduces a novel quantum hydrodynamic model accounting for independent spin states and their different occupations, revealing additional wave solutions in magnetized plasmas.

Findings

Four wave solutions instead of two in magnetized plasmas.

Separate spin evolution significantly alters wave behavior.

New wave modes arise from spin state considerations.

Abstract

We consider quantum plasmas of electrons and motionless ions. We describe separate evolution of spin-up and spin-down electrons. We present corresponding set of quantum hydrodynamic equations. We assume that plasmas are placed in an uniform external magnetic field. We account different occupation of spin-up and spin-down quantum states in equilibrium degenerate plasmas. This effect is included via equations of state for pressure of each species of electrons. We study oblique propagation of longitudinal waves. We show that instead of two well-known waves (the Langmuir wave and the Trivelpiece--Gould wave), plasmas reveal four wave solutions. New solutions exist due to both the separate consideration of spin-up and spin-down electrons \textit{and} different occupation of spin-up and spin-down quantum states in equilibrium state of degenerate plasmas.