Magnetic and Transport Properties of Iron-Chromium - Metallic Glasses.
The electrical resistivity, magnetoresistivity, the thermoelectric power, the magnetization and the Mossbauer effect have been studied in a series of Fe(,80-x)Cr(,x)B(,20) (0 (LESSTHEQ) x (LESSTHEQ) 32) metallic glasses. The electrical resistivity was measured in the temperature interval 0.1 to 300 K and in magnetic fields up to 4.3 T. The results show the presence of two effects: one of non-magnetic origin, caused by electron-electron interaction in a highly disordered system and the other of magnetic origin, probably the Kondo effect. The high field isotropic magnetoresistivity was also examined in detail and was found to be inconsistent with all currently available models. Results of a detailed investigation of the ferromagnetic anisotropy in the resistivity are included and discussed in the light of existing theories. The first direct observation in metallic glasses, of the classical phenomena known as excess resistivity due to the domain structure is also presented. The thermoelectric power of Fe-Cr-B and Fe-B for compositions in the range 13 to 22 at .% B has been measured from 4.2 to 550 K. The thermopower is extremely sensitive to B and Cr concentration and highly non-linear with temperature. A semi-quantitative explanation of the data is given, which emphasizes the importance of magnetic scattering. The a.c. magnetic susceptibility and d.c. magnetization as a function of field and temperature was measured in the Fe-Cr-B series of alloys. Samples with x (LESSTHEQ) 28 show ferromagnetic ordering which follows scaling law predictions yielding well defined values of the critical indices. Mossbauer spectra of these alloys as well as of the Fe-B glasses have been analysed to yield hyperfine field distribution, isomer shift, quadrupole splitting and correlations between these parameters. It is shown that in Fe-Cr-B glasses magnetic and non-magnetic iron sites coexist in the ferromagnetic phase and that Fe sites having more than 4 Cr near neighbours are essentially non -magnetic.
- Pub Date:
- Physics: Condensed Matter