Electrical Resistance and Magnetoresistance in Quasi-Crystalline and Amorphous Al–Mn Alloys

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Abstract
Temperature and magnetic field dependences of the electrical resistance R ( T , H ) of a quasi-crystalline (QC) Al–22.5 at%Mn and its counterpart amorphous (AM) alloys have been studied. Little difference in R ( T , H ) between these two phases is observed accompanying the following common characteristics. The resistance in the absence of magnetic field has a -log T dependence which holds down to near the spin-glass freezing temperature T f (8.5 K for QC, 7.4 K and 10 K for AM: Al–22.4 and -24.3 at%Mn, respectively). Below T f , R ( T ) deviates downward from the -log T curve. A negative magnetoresistance is observed at low temperatures below 10 K and monotonically enhanced on cooling. These behaviors may be understood in terms of the Kondo effect in a spin-glass state.