engleski

Hall effect in amorphous Al-W thin films

Thin films of amorphous AlxW100-x alloys (63<x<86) have been prepared by magnetron codeposition of pure metals onto glass substrates. The magnitudes of Hall coefficient, RH, measured at room temperature and at 77K are the same, up to the experimental error which is smaller than 10-12 m3/As. However, the RH value is strongly dependent upon the alloy composition, and, furthermore, it acquires positive values in the 64<x<76 composition range. The measured RH values range from -6*10-11 m3/As for Al86W14 up to 3*10-11 m3/As for Al67W33 alloy. The departure of Hall coefficient magnitudes from the values corresponding to the free-electron model, and its positive sign in amorphous metals, are attributed to a) the effects of the electronic band hybridization and/or b) possible magnetic contribution, i.e. to the anomalous (spontaneous) Hall effect. It is expected that the magnitude of the anomalous Hall effect in amorphous alloys is proportional to the square of electrical resistance. However, the value of electric resistance of the investigated amorphous alloys noticeably (10%) changes in the examined temperature interval (77-300 K), unlike the Hall coefficient magnitude. This way, a significant magnetic contribution to the Hall effect in amorphous Al-W alloys is reasonably excluded. The importance of the electronic bands hybridization (sp-d hybridization in actual case) for the interpretation of the measured variation of Hall coefficient is supported by a strong concentration-dependence of the structural relaxation of Al-W alloys, observed through the measurements of electrical resistance in a wide temperature range.

Hall effect; Al-W; thin films

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