High field transitions in (Fe,T)3Ga4 alloys

Magnetization of a series of transition metal alloys (Fe1-xTx)3Ga4 with T=Mn, V, Cr and Ti having values of x in the range 0.05≤x≤0.2 has been examined as a function of the magnetic field (0-12 T) and temperature (4-300 K). The alloys have the same base-centred monoclinic crystal structure as Fe3Ga4 and, in general, show a low field metamagnetic transition similar to that seen for Fe3Ga4. In the low temperature regime, many of the alloys also show an apparent first order transition at much higher fields ( similar 6 T) to a ferromagnetic state. The large hysteresis associated with this transition may indicate a magnetostrictive origin. Preliminary neutron diffraction results obtained at ISIS indicate that a small lattice contraction occurs in transforming to the antiferromagnetic state. The magnetic phase diagrams are interpreted in terms of theoretical results by Moriya and Usami [Solid State Commun. 23 (1977) 935] and Isoda [J. Phys. Soc. Japan 53 (1984) 3587] on magnetic phase transitions in itinerant electron systems. (orig.)