  Topological electromagnetism owing to nontrivial momentum-space topology of
electrons in insulators gives rise to diverse anomalous magnetoelectric
responses. While conventional inductors and capacitors are based on classical
electromagnetism described by Maxwell's equations, here we show that
topological electromagnetism in combination with spin dynamics in magnets also
generates an inductance or a capacitance. We build a generic framework to
extract the complex impedance on the basis of topological field theory, and
demonstrate the emergence of an inductance or a capacitance in several
heterostructure setups. In comparison with the previously-studied emergent
inductances in metallic magnets, insulators highly suppress the power loss,
because of the absence of Joule heating. We show that the inductance from
topological electromagnetism is achieved at low current and high frequency, and
is also advantageous in its power efficiency, as characterized by the high
quality factor (Q-factor).
