A logic circuit that can reconfigure its functions in a nonvolatile manner
and a single-electron transistor to be used in the logic circuits are
provided. The logic circuit has a single-electron spin transistor that
includes: a source; a drain; an island that is provided between the
source and the drain, and has tunnel junctions between the island and the
source and drain; and a gate that is capacitively coupled to the island.
In this logic circuit, at least one of the source, the drain, and the
island includes a ferromagnetic material having a variable magnetization
direction.