Magnetoresistance of a HgTe/CdHgTe double quantum well in an in-plane magnetic field

A magnetic field parallel to the layers of a double quantum well with conventional semiconductor constituents leads to a relative shift of the conduction band spectra of the constituent layers along the wave vector perpendicular to the field. If the states of the layers are tunnel-coupled, a tunneling gap is formed at the intersection of the single-layer spectra and is shifted upward with increasing field. This leads to striking features in the magnetoresistance caused by intersections of the Fermi level with the edges of the tunneling gap. Similar studies of transformations of the spectrum of the double quantum well in a HgTe/CdHgTe heterosystem, which has a p-type conductivity and HgTe layers with a gapless inverse energy spectrum, are reported in this work. Our experiments and corresponding calculations in the eight-band kp approach indicate that the evolution of the magnetoresistance with the variation of the in-plane field here has a much more complex and diverse character depending qualitatively on the thickness of the layers.