Demonstration of magnetic field imaging in a permalloy film with neutron spin phase contrast imaging

Hayashida, Hirotoshi; Yamazaki, Dai  ; Ebisawa, Toru*; Maruyama, Ryuji   ; Soyama, Kazuhiko  ; Tasaki, Seiji*; Hino, Masahiro*; Matsubayashi, Masahito  

In a neutron spin interferometer (NSI), incident neutrons are in states of up- and down-spin eigenstates and a phase difference between the eigenstates is observed after transmission through a magnetic sample. Since the phase difference is proportional to an integral of magnetic field along a trajectory of neutrons, NSI imaging provides projection images of a distribution of magnetic field in the sample. We tried to visualize magnetic field in permalloy film with and without stress as a demonstration of the NSI imaging. An experiment was carried out at C3-1-2-2, MINE2 port at the neutron guide hall of JRR-3M with wavelength of 0.88nm and wavelength resolution of 0.3% in FWHM. Permalloy film with thickness of 0.1 mm was used as a sample and was stressed by bending with angles of 45 and 180 . As a result, images of decrease of a saturated magnetization and an increase of leak magnetic field with increasing the bending angle were obtained.