New Type of Oscillatory Magnetoresistance in Metals

The magnetoresistive properties of a thin sodium wire have been studied at 1^∘{}K in transverse magnetic fields (HT) up to 60 000 gauss. This study was undertaken in order to determine whether magnetoresistive oscillations of the de Haas-van Alphen type could be detected in the vicinity of 60 000 gauss. Although no such oscillations were found, the magnetoresistance for HT below 15 000 gauss exhibited a completely new type of oscillatory phenomena. These new oscillations are periodic in H with a decreasing amplitude in increasing magnetic fields, whereas the de Hass-van Alphen oscillations would be periodic in H^-1 with an increasing amplitude in increasing magnetic fields. The period of these new oscillations is in excellent agreement with the period of the oscillatory behavior predicted theoretically by Sondheimer for the magnetoresistance due to surface scattering of thin metallic films in HT. From this period, a value for the electronic momentum was obtained. The significance of these new oscillations is discussed.