Effect of Alloying on Magnetic Breakdown in Zinc

Abstract

In the course of torsion measurements¹ of the de Haas-van Alphen periods in zinc-copper alloys, it became apparent that the high-field amplitude of the “needle” period showed a nearly normal field dependence, in contrast to the anomalously low amplitude in pure zinc.² Computations have been made to interpret the changing field dependence in terms of magnetic breakdown³ effects. Our results in pure zinc are in qualitative agreement with those of Lawson and Gordon,² with certain quantitative differences which are presumably due to differences in approach. Since breakdown effects become apparent at about 3 kG, our magnetic field range of 1 to 30 kG results in a wide range of breakdown probability, in an attempt to provide a stringent test of any theoretical interpretation. In the high-field region the hyperbolic sine term in the Lifshitz formula⁴ may not be replaced by the exponential approximation. The computations are therefore unwieldy, and were carried out on the IBM 709 computer. The amplitude of the DHVA oscillations was measured at three temperatures and at about ten angles in the (112̄0) and (101̄0) planes in pure zinc and in the (101̄0) plane in Zn-0.14 at. % Cu, and Zn-0.21 at. %Cu alloys. The computer first uses the temperature dependence of the amplitudes to calculate the effective mass, varying the mass iteratively⁵ until equation (1) is satisfied.

Supported by the Advanced Research Projects Agency, through the Northwestern University Materials Research Center, and by the National Science Foundation.