Magic Angle Effects and AMRO as Dimensional Crossovers

It is shown that interference effects between velocity and density of states, which occur as electrons move along open orbits in the extended Brillouin zone, result in a change of wave functions dimensionality at Magic Angle (MA) directions of a magnetic field. In a particular, we demonstrate that these 1D -> 2D dimensional crossovers result in the appearance of sharp minima in a resistivity component Rzz, perpendicular to conducting layers, which explains the main qualitative features of MA and Angular Magneto-Resistance Oscillations (AMRO) phenomena observed in low-dimensional conductors (TMTSF)2X, (DMET-TSeF)2X, and a-(BEDT-TTF)2MHg(SCN)4.