We have developed a noncontact technique of resistivity measurement in pulsed high magnetic fields of up to 40 T with use of a tunnel diode oscillator. An LC tank circuit powered by a tunnel diode oscillates at frequency of f∼1/LC, which is typically in a megahertz range. A sample is placed in the tank coil, and a small change in the resonant frequency f of the circuit is measured. For metals, the frequency change is related to the change in skin depth, which is converted to resistivity via δ=ρ/πμf. In order to read out the frequency change from frequency modulated (FM) signals in a short time, we utilize an integrated circuit of portable FM radio as FM demodulator. This FM demodulator is found to be highly sensitive and useful for highly conducting samples of the order of milliohms. We will show some examples of resistivity measurements applied to oxide and organic metals in pulsed magnetic fields of up to 40 T.

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