Spin-Charge Separation

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As a spin-charge separation is referred to a process in which the spin and charge of an electron separately as spin or charge waves in a Luttinger liquid can move. These separate spins and charges can be understood as quasiparticles which only have the respective quantum number of the electron. These quasiparticles are the spinon and the holon .

The Luttinger liquid

Since the usual model of the quantum fluid fails in a one-dimensional system ( Peierls instability ), another description is needed to describe interacting fermions in such a system.

The Luttinger fluid is one such model. With this z. B. Describe electrons in carbon nanotubes and artificial quantum wires .

The process of spin-charge separation

If the system experiences an external disturbance, density waves occur , which quantum mechanically can be understood as (bosonic) quasiparticles, the plasmons . There are also spin density waves and charge density waves that move at Fermi speed , ie at “normal” speed. These can be understood as ordinary waves , i.e. described with a one-dimensional wave equation . A special feature is that these waves only have one quantum number of the electron and no other quantum number .

Clearly speaking, this means that the charges (spins) of the entire system change one after the other due to the adjacent charges (the adjacent spins) if this one-dimensional system is subjected to a single-particle excitation (such as the addition of another fermion). These “disturbances” or “changes” in the spins (charges) can be understood as quasiparticles, in the example of the spin density waves the spinon and in the case of the charge density waves the holon.