Anderson-Higgs Mass of Magnons in Superconductor-Ferromagnet-Superconductor Systems

The Anderson-Higgs mechanism of mass generation is a generic concept in high-energy and condensed-matter physics. It shows up through the Meissner effect providing the expulsion of static and low-frequency magnetic fields from superconductors. However, it does not affect propagating electromagnetic waves with a spectrum gap determined by the plasma frequency, which is too large to be sensitive to the superconducting transition. Here we demonstrate the spectroscopic manifestation of the Anderson-Higgs mass, showing that it determines the spectrum gap of magnons in superconductor/ferromagnet/superconductor multilayers. Moreover, we show that this effect has been observed in recent experiments as a spontaneous ferromagnetic resonance frequency shift in such systems. Our theory explains many unusual experimental features and suggests effective controls over the magnon spectrum with tunable spectral gap and group-velocity reversal. These findings pave the way to a wide range of advanced functionalities for possible applications in magnonics.