Magnetically Modulated Resistance Techniques
The method of magnetically modulated resistance (MMR) is a variant of resistance vs. temperature measurements in which the magnetic field dependence of resistance vs. temperature is measured. This general technique is particularly useful for study and characterization of superconductors because the superconducting phase transition and weak link effects, present in granular samples, are magnetic field dependent. Because the field dependence of the intrinsic phase transition is different from that of extrinsic effects due to granularity, it is possible to separately identify MMR responses due to these effects. Thus the species dependent and sample dependent responses can be separately recorded. Another important aspect of this technique is its anisotropic response to macroscopically oriented samples. This allows detection of oriented weak link structures in single crystals1,2 which would be difficult, if indeed possible, by other methods. In this paper, we present an overview of this method and some examples from recent studies.
KeywordsElectron Spin Resonance Weak Link Microwave Absorption Superconducting Phase Transition Josephson Tunneling
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