Stabilization of the Polarity of (NdSmDy)(FeCo)B Permanent Magnets for Application in Magnetic Undulators

Abstract

The temperature dependences of the magnetization of polycrystalline samples of (NdSmDy)(FeCo)B sintered permanent magnets are measured in various magnetic fields by a SQUID magnetometer. Near T = 110 K, the spin-reorientation transition occurs. Bistable magnetic states with two equally possible orientations of the magnetization vector corresponding to different polarities of the permanent magnet are formed in the samples near the spin-reorientation transition. The polarity of the sintered magnets can be stabilized by a small external magnetic field of ∼250 Oe. It provides new possibilities for the application of these magnets in cryomagnetic systems such as magnetic undulators.