Study On Electronic Transport Properties Of Fe-based Bulk Amorphous Alloys

In the past thirty years, the electrical resistance and its temperature behavior havebeen widely investigated in amorphous alloys, and some important results related todisorder structure and magnetic effects have been obtained. Fe-based metallic glasses,which are normally ferromagnetic, sometimes show resistance minima behavior at atemperature (Tmin) and it is very interesting that the resistance minimum coexists withstrong ferromagnetism in Fe-based amorphous alloys s. The appearance of theresistance minimum has been ascribed to the disorder atomic structure or magneticeffects in the literature, but it is difficult to discern these effects since they oftenfunction together and sometimes lead to a second minimum. In Fe-based amorphousalloys, the magnetic order can be progressively suppressed without significantchanges in structure by substituting magnetic atoms, and we can get a systematicsurvey on electronic transport properties to help us understand the scatteringmechanismof these alloys. Measurements of the electrical resistance and the field dependence of resistanceof Fe61Co7Zr10Mo5-xNixW2B15 (x = 0, 1, 3, 5) bulk metallic glasses between 1.9 K and300 K are reported. A sign change of temperature coefficient of resistance (TCR) wasobserved when the concentration of Mo decreased. An interesting result is that aminimum of the resistance appeared at near room temperature for theFe61Co7Zr10Mo5W2B15 sample. By substituting Ni for Mo, the resistance minimumdisappeared. When all Mo atoms was substituted by Ni, the minimum appeared again,but at very low temperature. The resistance minima at high and low temperatures areinterpreted in terms of Kondo scattering and the Coulomb interaction mechanisms,respectively. The change of TCR is explained in terms of the extended Ziman theoryand the absence of minimum during the substitution provides us a clear boundary todiscern the minimum induced by the disorder atomic structure and magnetic effects.The field dependence of resistance measurements have confirmed that the resistanceminimum in sample without Ni addition is originated from Kondo effect and suggestthe TCR change may be ascribed to the change of Fermi lever during the substitution.