Role of an order-disorder phase transition in increasing the exchange magnetic field in a diluted magnetic semiconductor -: art. no. 220402

The controlled substitution of Mn by Zn within the diluted magnetic semiconductor Zn1-xMnxGa2Se4 (0 less than or equal tox less than or equal to1) series induces a pumping of magnetic ions from a defined site of the crystal lattice to another one driving the system to an order-disorder phase transition with x(c) = 0.50 +/- 0.01. A long-range order parameter, eta, is defined and directly determined as a function of x within the whole range of composition from neutron-diffraction experiments, An augmentation of the magnetic exchange field by increasing the magnetic dilution occurs as a consequence of that order-disorder process.