Iv. Transportelectronic Structure of Eub6, Transport and Magnetic Properties

In non-magnetic RB,, it is shown that the most common defect R vacancy can trap third hole creating a compensating conduction electron due to the narrow gap semiconductor character. The latter is trapped loosely and thus easily causes n-type character. Various transport properties are explained on this model. In magnetic EuB,-, the above defect center makes a giant moment cluster. Furthermore, due to the antiBonding effect with the 4f levels, the valence bands of the parallel spin are pushed up into the conduction bands in ferromagnetic state creating many conduction electrons . Various anomalous magnetic and magneto transport properties are explained on this model.