Abstract
77Se NMR measurements have been performed in the normal state of the organic, magnetic field induced Superconductor λ(BETS)2FeCl4, to examine the interaction between Fe local spins and π conduction electrons. Large, negative Knight shift values were observed at fields lower than the one corresponding to onset of field induced superconductivity. This evidences that the conduction electrons feel a negative internal field coming from the Fe spins through the exchange interaction \(J{\vec{s}}\cdot {\vec{S}}\). This suggests that the superconductivity induced by high magnetic fields has its origin in the Jaccarino–Peter compensation mechanism. The estimated value of the exchange interaction J, is 30% smaller than that predicted by the resistivity measurements.
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Hiraki, K., Mayaffre, H., Horvatic, M. et al. π-d Interaction in the Field Induced Superconductor λ-(BETS)2FeCl4: Studied by 77Se NMR. J Low Temp Phys 142, 185–190 (2006). https://doi.org/10.1007/s10909-006-9017-y
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DOI: https://doi.org/10.1007/s10909-006-9017-y