SEMICONDUCTOR-METAL TRANSITION AND THE ONSET OF ITINERANT FERROMAGNETISM IN THE HEUSLER PHASES TICOSN-TICOSB

The magnetic and transport properties of the TiCoSnxSb1-x solid solutions with the cubic MgAgAs structure have been studied, and show the onset of ferromagnetism associated with a semiconductor to metal transition, keeping the same 3d elements and varying the number of s-p electrons. The transition from TiCoSn ferromagnetic metal to the non-magnetic semiconductor TiCoSb occurs through an intermediate metallic Pauli-like state. The variations of the Curie temperature as a function of saturation and effective paramagnetic moments are related to the itinerant ferromagnetism model. A comparison is made with the TiCoxNi1-xSn series, where the transition occurs directly from ferromagnetic metal to semiconducting state.