Fermi surface of LaAl2

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Abstract
A result is reported of a calculation of the energy bandstructure and the Fermi surface for the cubic Laves-phase LaAl2 by an APW method. To improve on a previous calculation by Switendick (1973) the energy bandstructure has been calculated self-consistently with the local-spin-density approximation and a relativistic approximation. The tenth band Fermi surface is a sphere centred at the Gamma point, but has bumps in (100) directions. Its extremal cross sectional areas agree within 3% with a result of recent de Haas-van Alphen measurements. The ninth-band Fermi surface is a multiply connected hole sheet, the topology of which is a junglegym running from an L point to a nearest-neighbour L point. The extremal orbits from small sheets around X and W points account reasonably well for the observed angular dependence of the low-frequency branches. The ninth-band Fermi surface predicts both (100) and (110) open orbits, consistent with the experimental result for the magnetoresistance.