The effect of silicon on the exchange interactions inGdxCe1−xCo4Si compounds

Abstract

The GdxCe1−xCo4Si compounds with x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0 crystallize in the hexagonal structure of theCaCu5 type, with thespace group P6/mmm. CeCo4Si exhibits anomalously low values of the elementary cell volume as wellas of the Curie temperature and the mean cobalt moment in theRCo4Si series(R = rare earth or yttrium). All compounds exhibit a ferrimagnetic-type ordering.Band structure calculations using the ab initio tight-binding linear muffintin orbital method in the atomic sphere approximation were performed forRCo4Si,R = Ce, Gd. The computations provide evidence that the induced Ce momentsare oriented antiparallel to the Co ones. The effect of Si and B atoms onthe R–Co exchange interactions and on the magnetic behaviour of Co inRCo4B/Si compounds is discussed comparatively.