title: Contactless measurement of nonlinear conductivity in the radio-frequency range.
abstract: We have developed a system for contactless measurement of nonlinear conductivity in the radio-frequency band, and over a wide temperature range. A non-resonant circuit is used to electrically excite the sample, and the induced signal is detected by a resonant circuit whose natural frequency matches higher harmonics of the excitation. A simple modification of the probe allows non-resonant detection suitable for stronger signals. Two measurement procedures are proposed that allow significant excitation power variation, up to 150 W. The apparatus has been validated through the measurement of the nonlinear response at the superconducting transition of a high-Tc superconductor, and the nematic transition of an iron pnictide.
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia.
authors.forename: Marija
authors.initials: M
authors.lastname: Došlić
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia.
authors.forename: Damjan
authors.initials: D
authors.lastname: Pelc
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, 10000 Zagreb, Croatia.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Požek