Contactless transport measurement of metals in pulsed high magnetic fields

A contactless method is developed for high-sensitivity magnetoresistance measurement in pulsed high fields. The resistivity is measured by observing transmission of a radio-frequency field through a thin specimen. The transmission rate is analytically given as a function of the resistivity within the classical skin-effect regime. By use of a high-frequency (0.1--100 MHz), electrical noise coming from pulsed magnetic fields can be rejected effectively and the sensitivity of the measurement is improved by at least a factor of 100 compared with that of a conventional dc four-terminal method. The present method is available for the measurements on superconductors, magnetic metals, and any other materials with short collision time in high magnetic fields. Upper critical fields and magnetoresistance of recent high T/sub c/ superconductors Y-Ba-Cu-O are measured up to 40 T