Stabilization of Reentrance AFM on Gd2Al System in a Certain Electron Concentration

Abstract

A random mixture of two compounds with different type of magnetic ordering which can lead to a new phase with different magnetic characteristics is studied. Such an interesting random magnetic system can be formed by a ferromagnet (e.g. Gd 2 Au) and antiferromagnetic system like e.g. Gd 2 Al with localized magnetic moments where, in principle, the dominant exchange interactions are those of the nearest neighbours. A systematic study on the solid solutions of the type Gd 2 (Al 1± ±x Au x ) is reported here. (I) The roles and effects of conduction electron concentration ªc.e.c.º on the magnetic structure, where the magnetic behaviour is shape dependent (0.2`x`0). (II) The cause of magnetic instability of Gd 2 Al, which should be due to the ªc.eº. (III) The critical stabilized point by decreasing ªc.e.c.º. It is shown that the magnetic phase of the pseudobinary intermetallic compound Gd 2 (Au x Al 1± ±x ) becomes unstable by increasing the conduction electron concentration through the variation in unit cell dimensions. It becomes stable at a critical value of c.e.c., where Se ij J ij 0, resulting in a paramagnetic behaviour (q p % 0 to 5) at x 0.3. It is shown that the instabilities of the crystal and magnetic structure are functions of c.e.c. and depend on the Fermi sphere K F which is the main cause of the shape dependence of the magnetic structure of the sample.