Patent ID: 8013701

Claim:
A magnetic circuit for storing a sample in a gap formed between a plurality of magnetic field application parts opposed to each other in parallel and applying a magnetic field to the sample, wherein each of the magnetic field application parts includes a plurality of permanent magnet segments, the permanent magnet segments including: a first permanent magnet horizontally magnetized in parallel with an opposed surface of the magnet field application part, a second permanent magnet magnetized perpendicularly to the opposed surface of the magnetic field application part, the second permanent magnet being provided on a north pole of the first permanent magnet, and a third permanent magnet perpendicularly magnetized in an opposite direction from the second magnet, the third permanent magnet being provided on a south pole of the first permanent magnet, wherein the magnetic field application parts are configured like a notched ring around a virtual axis with a combination of the plurality of first to third permanent magnets, the first permanent magnet is disposed such that the first permanent magnet is magnetized perpendicular to the virtual axis, and wherein the notched portion of the ring is formed by removing a part of the combination of first to third permanent magnets.