44 research outputs found
Canonical Formalism for Lagrangians of Maximal Nonlocality
A canonical formalism for Lagrangians of maximal nonlocality is established.
The method is based on the familiar Legendre transformation to a new function
which can be derived from the maximally nonlocal Lagrangian. The corresponding
canonical equations are derived through the standard procedure in local theory
and appear much like those local ones, though the implication of the equations
is largely expanded.Comment: 17 pages with 1 eps figur
A First-Principles Study of the Electronic Reconstructions of LaAlO3/SrTiO3 Heterointerfaces and Their Variants
We present a first-principles study of the electronic structures and
properties of ideal (atomically sharp) LaAlO3/SrTiO3 (001) heterointerfaces and
their variants such as a new class of quantum well systems. We demonstrate the
insulating-to-metallic transition as a function of the LaAlO3 film thickness in
these systems. After the phase transition, we find that conduction electrons
are bound to the n-type interface while holes diffuse away from the p-type
interface, and we explain this asymmetry in terms of a large hopping matrix
element that is unique to the n-type interface. We build a tight-binding model
based on these hopping matrix elements to illustrate how the conduction
electron gas is bound to the n-type interface. Based on the `polar catastrophe'
mechanism, we propose a new class of quantum wells at which we can manually
control the spatial extent of the conduction electron gas. In addition, we
develop a continuous model to unify the LaAlO3/SrTiO3 interfaces and quantum
wells and predict the thickness dependence of sheet carrier densities of these
systems. Finally, we study the external field effect on both LaAlO3/SrTiO3
interfaces and quantum well systems. Our systematic study of the electronic
reconstruction of LaAlO3/SrTiO3 interfaces may serve as a guide to engineering
transition metal oxide heterointerfaces.Comment: 50 pages, 18 figures and 4 table