Unexpected de Haas-van Alphen oscillation in 2D multiband systems due to chemical potential oscillation and its relevance to magnetic breakdown systems

In two-dimensional (2D) multiband metals, the interference through chemical potential oscillation (CPO), which is described in the text, is shown to cause conventionally unexpected frequency components in the de Haas-van Alphen (dHvA) oscillation; as an example, the numerical result for a two-band case is shown. Then, we discuss the relevance of the CPO to the appearance of the prohibited dHvA oscillation in 2D magnetic breakdown (MB) systems, where ''the prohibited dHvA oscillation'' means the one not permitted in the standard semiclassical theory which incorporates MB. From these, we propose that the CPO is the main cause of what is called the prohibited difference-frequency oscillation in the dHvA effect of kappa-(ET)(2)Cu(NCS)(2).