On the ferromagnetic-paramagnetic phase transition in amorphous iron-rich Fe100-xZrx (x=8, 9, 10) alloys

Abstract

With a view to resolving the controversy (see Kaul, 1987; Fish and Rhyne, 1987) surrounding the nature of the magnetic transition. Tc in amorphous (a-)Fe100-xZrx alloys with x=8, 9, 10, published magnetisation data on a-Fe92Zr8 and a-Fe91Zr9 alloys have been reanalysed and detailed bulk magnetisation measurements in the critical region have been performed on a-Fe90Zr10. Other workers have claimed that the critical exponents for spontaneous magnetisation, initial susceptibility and critical isotherm, i.e. beta , gamma and delta , respectively, have anomalously large values for a-Fe92Zr8 and a-Fe90Zr10 alloys, but the authors' data analysis demonstrates that for all the glassy alloys in question the critical exponents beta , gamma and delta possess values that are very close to the three-dimensional Heisenberg values and obey the Widom scaling relation, beta delta = beta + gamma . Consistent with this result, magnetisation data in the critical region do satisfy the magnetic equation of state characteristic of a second-order phase transition. A coherent explanation has been provided for the seemingly contradictory neutron diffraction and magnetisation results within the framework of a model previously proposed by the author. Moreover, recently published thermoelectric power and electrical resistivity data on a-Fe90Zr10 and a-Fe92Zr8, respectively, have also been discussed in the light of the present findings.