Reentrant spin glass behavior of BaTi 2Fe 4O 11

Abstract

BaTi 2Fe 4O 11 shows the reentrant spin glass behaviour in which T c and T f are 165 and 78.5 K, respectively. Mössbauer spectrum shows the broad sextet in the ferrimagnetic range of the reentrant spin glass. Magnetic relaxations are observed in the ferrimagnetic range as well as in the spin glass range, namely magnetization increases with log t after the application of external magnetic field and remanent magnetization decreases with time. At 4.2 K no relaxation effect is observed. At x> 0.2 in BaSn x Ti 2- x Fe 4O 13 the reentrant spin glass behavior changes into the spin glass behavior with a single cusp at 80 K. At x> 0.6 the cusp of ac susceptibility disappears and spin glass behavior almost disappears near the concentration of x = 2. Ti ions seems to break long range magnetic order in BaTi 2Fe 4O 11, making magnetic clusters while Sn ions expand lattice, resulting in the decrease of magnetic coupling energy and take regular atomic positions, decreasing the magnetic cluster.