Itinerant Electron Magnetism of Hexagonal La<SUB>2</SUB>Ni<SUB>7</SUB>

Abstract

Magnetizations of itinerant electron magnets La2Ni7 and related compounds with a hexagonal crystal structure were measured. Successive metamagnetic transitions were observed in La2Ni7, and H-T phase diagram of La2Ni7 was determined. The zero-field state may be antiferromagnetic for T<Tt1=54 K, and is a state of some kind (probably antiferromagnetic) with a very small ferromagnetic moment in Tt1<T<Tt2=66 K. Substitutions of Co or Cu for Ni show that the band structure of La2Ni7 tends to produce both ferromagnetic and antiferromagnetic states, favoring the application of the theory of Moriya and Usami. Their theory is applicable assuming a tendency to form two types of antiferromagnetic states and a tendency to form a ferromagnetic state.