MAGNETIC-PROPERTIES AND MAGNETIC PHASE-DIAGRAM OF FRUSTRATED CO1-XFEXPT3 COMPOUNDS

The investigation of the magnetic properties of the pseudobinary Co1-x FexPt3 L1(2) ordered compounds resulting from alloying ferromagnet CoP t3 and frustrated antiferromagnet FePt3 is reported. The magnetic phas e diagram of this system shows the presence of a pure spin glass phase that separates the ferromagnetic region from the antiferromagnetic on e. On the Co-rich side (x < 0.6), two re-entrant spin glass phases are found to emerge at low temperature in the ferromagnetic region. On th e iron-rich side, an antiferromagnetic region with two antiferromagnet ic [1/2 1/2 0] and [1/2 00] structures is observed for 1 greater than or equal to x greater than or equal to 0.8. This magnetic phase diagra m is discussed comparatively with the previously determined (Fe-Mn)Pt- 3 and (Co-Mn)Pt-3 phase diagrams. The randomness of the average exchan ge interaction is suggested to arise from a competition between the th ree dominant magnetic interactions J(CoCo), J(FeFe), and J(CoFe) of 3d atoms in sites of second nearest neighbors in the L1(2) structure. (C ) 1997 American Institute of Physics.