Study of Magnetic Phase Transition and Spin Frustration in Cobalt Aluminium Oxide Materials based on High Temperature Series Expansions Model

Abstract

The magnetic properties of 2 2 2 4 x x CoAl Co O − for 0 1 x ≤ ≤ are studied. The values of the nearest neighbour ( 1 J ), next-nearest neighbour ( 2 J ), intra-plane ( ) aa J and inter-plane ( ) , ab ac J J exchange interactions are calculated by the mean field theory for ordered region and by the probability law adapted of the nature of dilution problem in A-spinel lattice in spin glass region. The high-temperature series expansions have been applied in the 2 2 2 4 x x CoAl Co O − systems, combined with the Padé approximants method, to determine the Néel temperature ( ) N T K or freezing temperature ( ) SG T K in the range 0 1 x ≤ ≤ . The critical exponents associated with the magnetic susceptibility ( ) γ and the correlation lengths ( ) ν are deduced in the range ordered 0.3 1 x ≤ ≤ . The obtained values of γ and ν are insensitive to the dilution ratio x and may be compared with other theoretical results based on 3D Heisenberg model.PACS 75.30.Et, 75.40.Cx, 74.25.Ha, 75.30.Cr 302 R. Masrour and M. Hamedoun