Stabilization of reentrance AFM on Gd₂Al system in a certain electron concentration

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. Gd₂Au) and antiferromagnetic system like e.g. Gd₂Al 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 Gd₂(Al_1-xAu_x) is reported here. (1) The roles and effects of conduction electron concentration "c.e.c." on the magnetic structure, where the magnetic behaviour is shape dependent (0.2 < x < 0). (II) The cause of magnetic instability of Gd₂Al, which should be due to the "c.e". (III) The critical stabilized point by decreasing "c.e.c.". It is shown that the magnetic phase of the pseudobinary intermetallic compound Gd₂(Au_xAl_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 Σε_ij J_ij = 0, resulting in a paramagnetic behaviour (θ_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.