Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MA: Magnetismus

MA 19: Mikro- und nanostrukturierte magn. Materialien I

MA 19.2: Vortrag

Montag, 7. März 2005, 10:45–11:00, TU EMH225

Band Structure in Strong Magnetic Fields — •Manfred Taut — Leibniz Institute for Solid State and Materials Research, POB 270116, 01171 Dresden

The one–electron Schrödinger equation in a periodic effective potential and a homogenous magnetic field is solved for rational flux quantum numbers p/q and several lattice structures. A LCAO formalism is used. The total energy E_tot(B,z0)=∑_k,n^occ. ε_k,n(B) is calculated as a function of magnetic field B and of band filling z0. The magnetization M(B)=∇_B   E_tot(B,z0) shows novel oscillations.
The gap pattern of a two–dimensional magnetic band structure (e.g. the Hofstadter butterfly) can be puzzled together out of three basic quasi–classical spectra. The spectra around a certain flux quantum number p₀/q₀ can be obtained by quasiclassical quantisation of the exact magnetic band structure for p₀/q₀.
The total energy as a function of B shows kinks for integer filling factors (full Landau levels) and, in the high magnetic field regime, also for certain rational filling factors.
The exact magnetization contains information not only about the (zero–magnetic–field) band structure, but also about any finite–magnetic–field band structure. The asymptodic oscillations in M(1/(B−B₀)) provide the Fermi surface cross sections for the magnetic band structure at B₀. Unlike the standard Lifshitz–Kosevich type approaches, our magnetizations contain the effects of magnetic breakdown, forbidden orbits and interband coupling.