Materials, devices and methods related to below-resonance radio-frequency (RF) circulators and isolators. In some embodiments, a circulator can include a conductor having a plurality of signal ports, and one or more magnets configured to provide a magnetic field. The circulator can further include one or more ferrite disks implemented relative to the conductor and the one or more magnets so that an RF signal can be routed selectively among the signal ports due to the magnetic field. Each of the one or more ferrite disks can include synthetic garnet material having dodecahedral sites, octahedral sites and tetrahedral sites, with bismuth (Bi) occupying at least some of the dodecahedral sites, and aluminum (Al) occupying at least some of the tetrahedral sites. Such synthetic garnet material can be represented by a formula Y.sub.3-x-2yzBi.sub.xCa.sub.2y+zFe.sub.5-y-z-aV.sub.yZr.sub.zAl.sub.aO.sub.12. In some embodiments, x1.4, y0.7, z0.7, and a0.75.

Wafer-bonded inductors, transformers, and related electronic components can be used in power electronics and provide low conduction loss in the MHz-GHz frequency range. The wafer bonding fabrication process and its thermal requirements offer relatively simple and low cost manufacturing. The resulting devices offer a unique combination of high power handling at high frequencies and small form factor.