Microwave response and spin waves in superconducting ferromagnets

Abstract

Excitation of spin waves is considered in a superconducting ferromagnetic slab with the equilibrium magnetization both perpendicular and parallel to the surface. The surface impedance is calculated, and its behavior near propagation thresholds is analyzed. The influence of nonzero magnetic induction at the surface is considered in various cases. The results provide a basis for the investigation of materials with coexisting superconductivity and magnetism by microwave response measurements.

Spin Dynamics in a Superconductor-Ferromagnet Proximity System

“…On the other hand, there are by now several theoretical predictions concerning such experiments. In ferromagnetic superconductors the symmetry of the order parameter might be identifiable [8,9], while S=F=S junctions are to show unconventional spin wave dynamics [10], or conductance resonances in the presence of precessing spins [11]. Here we address the first basic question in this field, namely, the effect of the proximity of a superconductor (Nb) on the FMR linewidth of a strong ferromagnet (Ni 80 Fe 20 , Permalloy, Py) and find significant changes in the homogeneous broadening.…”

Microwave and dc response of an Abrikosov vortex lattice in ferromagnetic superconductors

“…This effect has been investigated theoretically by Buzdin in the case of superconducting antiferromagnet [8]. For a ferromagnetic superconductor in the Meissner state, different types of spin waves have been previously analyzed, including bulk magnons [9,10], domain wall waves [11] and surface waves [12].…”

“…The preceding papers [15][16][17][18][19] mainly concentrated on flux dynamics in superconducting antiferromagnets. In the present paper we analyze the influence of the vortex-magnetic moment interaction on the microwave and dc responses of a ferromagnetic superconductor in the mixed state (the Meissner state has been considered in [9,10]).…”

“…It will be important for us that the magnetic field h e of the probing electromagnetic wave be parallel to the magnetization easy axis (directed along the vector M 0 ), so that magnon modes propagating along the z-axis are not excited (see Refs. [9,10,14]). Then, in a wide range of parameters the following simple expression for the surface impedance is valid [21]:…”

Band structure of magnetic excitations in the vortex phase of a ferromagnetic superconductor

“…6 Spin waves in magnetic superconductors in the Meissner state have been studied theoretically, using different phenomenological approaches, in several papers. [6][7][8][9][10] determined the magnon spectrum in an antiferromagnetic superconductor with an easy-axis anisotropy. Braude and Sonin 6,9 calculated the magnon spectrum and the microwave response of a ferromagnetic supercondutor.…”