Asymmetric unit cells can also cause spin-orbit coupling (e.g. Rashba effect) or altermagnetism (recently discovered effect), so it depends on the asymmetry type.
The effective mass of an electron is related to d^2E(k)/dk^2 where E(k) is the electron band structure. If E(k) is linear in k_x but parabolic in k_y, the effective mass is zero in the x direction but finite in the y direction. But as far as I know, it is not possible to make the mass finite in the +x direction but zero in the -x direction.
I’m actually not sure. Do you know of such a material, with that kind of asymmetric band structure in equilibrium?
I would expect such a material as you linked to have a momentum imbalance in the x direction, which leads to mass transport in the x direction, until a new equilibrium is achieved.
I would expect such a material as you linked to have a momentum imbalance in the x direction, which leads to mass transport in the x direction, until a new equilibrium is achieved.
That makes sense. So it electrons will flow in one direction until there is a static electric field that create a slope in the fermi level. Perohaps https://en.wikipedia.org/wiki/Electret
It says that quartz is an electret, but I can't find the band structrure.
Comments
Asymmetric unit cells can also cause spin-orbit coupling (e.g. Rashba effect) or altermagnetism (recently discovered effect), so it depends on the asymmetry type.
The effective mass of an electron is related to d^2E(k)/dk^2 where E(k) is the electron band structure. If E(k) is linear in k_x but parabolic in k_y, the effective mass is zero in the x direction but finite in the y direction. But as far as I know, it is not possible to make the mass finite in the +x direction but zero in the -x direction.
What happens in a half filled asymmetric band? Like https://imgur.com/a/half-filled-asymetric-band-P7NQ7zU
A new electron will fall in places with different curvature if you choose one direction or the other.
Or the mass is calculated as the average because an electric field must remove an electron form one side and put it in the oher?
(I took my solid physics class too many years ago, I don't remember the details and I never understood all of them anyway.)
I’m actually not sure. Do you know of such a material, with that kind of asymmetric band structure in equilibrium?
I would expect such a material as you linked to have a momentum imbalance in the x direction, which leads to mass transport in the x direction, until a new equilibrium is achieved.
That makes sense. So it electrons will flow in one direction until there is a static electric field that create a slope in the fermi level. Perohaps https://en.wikipedia.org/wiki/Electret
It says that quartz is an electret, but I can't find the band structrure.