Charged Domain Walls:
	- Domain wall is the interface between two chemically equivalent regions with different polarization, strain or magnetic vectors
	- Homo-interface between two domains
	- Polarization diverges at the interface
		- Gives net charge at the interface
	- Ferroelastic vs. non-ferroelastic
		- Special cases: Improper and weak ferroelectrics
		- In proper ferroelectrics the polarization gives rise to a spontaneous strain (unit cell distortion). Ferroelastic domain walls cannot have lattice mismatch because of increased energy. Can be mechanically stabilized.
		-  Non-ferroelastic domain walls have identical strain in adjacent domains (f.eks. 180 perovskites). Cannot be mechanically stabilized.
	
	- (mirror) symmetric vs. non-symmetric with respect to polarization
		- non-symmetric: Formed during domain nucleation, can be stabilized by clamping, electric/elastic field gradients and pinning
		- Symmetric: Can be stabilized by mechanical compatibility or free carriers (no external forces!!)

	- CDW can be stabilized by several mechanisms, the one we are going to look at is stabilization by free carriers. Depolarizing field is strong enough to make it energetically favorable for electrons/holes to move to the wall, even in normally insulating materials.
		- can also be stabilized by mobile dopants and defects


Conduction at CDW's:
	- head-head / tail-tail : Depends on the material (n-doped or p-doped)
	- Oxygen vacancies can accumulate at tail-tail walls
	- Tail-tail conduction: p-type electrode donates holes 

Application:
	- In-plane vs. out-of plane
	- Out of plane has trouble with wall drift and wall stability
	- Structure utilizing the "dead layer"
		- What is a "selector"?
	- Electrode placement / form