Superconducting magnetic bearing

1. A superconductive magnetic bearing comprising:

a stationary bearing portion having an annular superconductor unit provided on a fixed portion; and

a rotatable bearing portion having an annular permanent magnet unit provided on a rotary portion so as to be opposed to the superconductor unit,

wherein the superconductor unit includes a plurality of circumferentially divided superconductor bulks, the adjacent superconductor bulks coming into contact with each other without a gap to constitute the superconductor unit, and the rotary portion being contactlessly supported relative to the fixed portion by the pinning effect of a superconductor constituting the superconductor unit,

wherein in order to reduce a rotation loss of the rotatable bearing portion due to unevenness of magnetic fields occurring by the construction that the superconductor unit includes the plurality of superconductor bulks circumferentially divided and that the adjacent superconductor bulks comes into contact with each other without a gap, the rotatable bearing portion includes the annular permanent magnet unit and an annular yoke adjacent to the permanent magnet unit and opposed to the superconductor unit,

wherein the permanent magnet unit includes a plurality of permanent magnet members arranged in superposed layers with an insulating layer provided between each adjacent pair of magnet members,

wherein the yoke includes a plurality of yoke members made of a magnetic material and arranged in superposed layers with an insulating layer interposed between each adjacent pair of yoke members, and

wherein the insulating layers of the yoke members directly contact an entire area of a contact surface of each adjacent yoke member.