Photoemission study of valence electrons in La(Co1-xFex)13 (x=0,0.2).

Abstract

The electronic structure of La(Co{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 13} ({ital x}=0,0.2) has been investigated by using photoemission spectroscopy. The La 5{ital d} and {ital T} 3{ital d} ({ital T}=Fe,Co) partial spectral weights (PSW`s) are extracted and compared with the calculated angular momentum projected densities of states (PLDOS`s). No Co 3{ital d} satellite is observed, impling a weak Co 3{ital d} Coulmb correlation in this system. La 5{ital d} emissions exhibit a weak enhancement near the La 4{ital d} absorption edge, from which the La 5{ital d} PSW`s of La(Co{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 13} ({ital x}=0,0.2) have been extracted. For a given {ital x} in La(Co{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 13}, the overall features of the La 5{ital d} PSW, such as bandwidths and long tails, are rather similar to those of the {ital T} 3{ital d} PSW, indicating a large hybridization between the {ital T} 3{ital d} and La 5{ital d} states. The experimental Co 3{ital d} and La 5{ital d} PSW`s of LaCo{sub 13} show a large disagreement with the calculated PLDOS`s. With a substitution of Fe for Co, the PSW`s of La(Co{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 13} remain nearly unchanged between {ital x}=0 and 0.2, whichmore » is contradictory to the predicted changes in the PLDOS`s obtained in the rigid-band scheme. This finding suggests a breakdown of a simple rigid-band approximation in La(Co{sub 1{minus}{ital x}}Fe{sub {ital x}}){sub 13}, which is probably due to a large hybridization bonding between Co and Fe 3{ital d} electrons.« less