As a simple model for lattice defects like grain boundaries in solid state physics we consider potentials which are obtained from a periodic potentialshown that the Schrödinger operators H t = − + W t have spectrum (surface states) in the spectral gaps of H 0 , for suitable t ∈ (0, 1). We also discuss the density of these surface states as compared to the density of the bulk. Our approach is variational and it is first applied to the well-known dislocation problem (Korotyaev (2000(Korotyaev ( , 2005 [15,16]) on the real line. We then proceed to the dislocation problem for an infinite strip and for the plane. In Appendix A, we discuss regularity properties of the eigenvalue branches in the one-dimensional dislocation problem for suitable classes of potentials.
As a simple model for lattice defects like grain boundaries in solid state physics we consider potentials which are obtained from a periodic potentialshown that the Schrödinger operators H t = − + W t have spectrum (surface states) in the spectral gaps of H 0 , for suitable t ∈ (0, 1). We also discuss the density of these surface states as compared to the density of the bulk. Our approach is variational and it is first applied to the well-known dislocation problem (Korotyaev (2000(Korotyaev ( , 2005 [15,16]) on the real line. We then proceed to the dislocation problem for an infinite strip and for the plane. In Appendix A, we discuss regularity properties of the eigenvalue branches in the one-dimensional dislocation problem for suitable classes of potentials.
“…Assuming either (4) Remark 2.1. With these results in hand we may conclude that the singular continuous component in the spectrum of H is empty [20].…”
Section: Absolute Continuity Of the Hamiltonianmentioning
Abstract. We prove absolute continuity for an extended class of two-dimensional magnetic Hamiltonians that were initially studied by A. Iwatsuka. In particular, we add an electric field that is translation invariant in the same direction as the magnetic field is. As an example, we study the effective Hamiltonian for a thin quantum layer in a homogeneous magnetic field.
“…We let (N,x) [1,2]). The singular spectrum of the operator D + W is empty and the eigenvalues (if they exist) have an infinite multiplicity and form a discrete set (see [3] and also [4], the last statement can also be easily derived from results of [5]). If there are no eigenvalues in the spectrum of the operator D + W , then the spectrum is absolutely continuous.…”
Absolute continuity of the spectrum of a 3D periodic magnetic Dirac operator is proved provided that the magnetic potential A belongs to the space H q loc , q > 1, and the matrix potential V ∈ L 3 loc is represented in the form V = V0 + V1, where V0 commutes and V1 anticommutes with the Dirac matrices αj, j = 1, 2, 3.
Mathematics Subject Classification (2010). Primary 35P05, 35Q40; Secondary 81Q10.Keywords. Dirac operator, periodic potential, absolutely continuous spectrum.
IntroductionLet M M , M ∈ N, be the linear space of complex (M × M )-matrices, S M the set of Hermitian matrices from M M . Matrices α j ∈ S M , j = 1, . . . , d (d 2), are assumed to satisfy the anticommutation relations α j α l + α l α j = 2δ jl I, where I ∈ M M is the identity matrix and δ jl is the Kronecker delta. Let S M be the subset of S M that consists of matrices L represented in the form L = L 0 + L 1 , where L s ∈ S M and α j L s = (−1) s L s α j for all j = 1, . . . , d, s = 0, 1. Consider the d-dimensional Dirac operator d j=1The matrix function V : R d → S M and the components A j of the magnetic potential A : R d → R d are supposed to be periodic with a common period lattice Λ ⊂ R d . In particular, the matrix function V can be chosen in the form
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