Development of instruments for imaging of local magnetic structure by magnetic neutron holography

We have developed instruments for magnetic neutron holography (MNH) using polarized white neutrons to investigate the local magnetic structures of magnetic alloys. We chose the 3He spin filter method as the neutron polarizer to polarize neutrons over a wide wavelength range of up to a few 100 meV. We developed a magnet device to saturate the magnetizations of ferromagnetic samples, and instruments to transport polarized neutrons from a 3He spin filter to the MNH sample. The neutron polarization, Pn, at the beginning of the MNH experiments was confirmed to be 0.46, which is feasible for MNH. Using the developed instruments, we obtained preliminary results for the room-temperature ferromagnetic alloy Fe0.08Co0.92. Technical problems encountered in the experiments and ways to overcome them are discussed. Based on these results, we believe that MNH that use polarized neutrons is promising.