Comment on “Exchange instabilities in semiconductor double-quantum-well systems”

Semiconductor double-quantum-well systems in the low-density regime are prone to magnetic and charge-transfer instabilities. While recent calculations, using both a pseudospin approach and a local-spin-density approximation (LSDA) [Phys. Rev. B 55, 4506 (1997)] seem to rule out the instability towards a monolayer configuration, the present contribution is devoted to refuting this conclusion in the LSDA. In this approximation, it is found that there is a charge-transfer instability for barrier widths that are neither too small nor too large.