Magnetic breakdown in aluminium

Abstract

Magnetic breakdown effects in Al were investigated by transverse magnetoresistance measurements on specimens with (100), (110), (111) and (112) current directions. The rotation diagrams of the magnetoresistance exhibit small anisotropies which agree with earlier measurements using different experimental techniques and with calculations on the basis of a closed Fermi surface model for Al. Superimposed on this small anisotropy characteristic peaks occur which are attributed to magnetic breakdown. In the field dependence a strong linear increase of the high-field magnetoresistance is observed for all specimen orientations affected by magnetic breakdown, thus demonstrating that magnetic breakdown is responsible for, or at least amplifiers, the linear high-field magnetoresistance in Al. For the magnetic field B//(001) the magnetoresistance oscillates periodically in 1/B. The various effects of magnetic breakdown on the magnetoresistance are explained by consideration of the different geometries of breakdown orbits which can occur in Al.