Neutron Spin Echo Optics Through Magnetic Multilayer Films and Magnetic Crystals

Here we have established neutron spin echo (NSE) optics by observing spin precession through magnetic Fabry-Perot films of [Permalloy45(Fe₅₅Ni₄₅)(abbreviated as PA)-Ge]''-PA with n=10 including the tunneling region, through multilayer film of (PA-Ti)'' with n=15 at the Bragg condition, as well as through helical magnetic crystal of holmium at the Bragg conditions using a forward scattering (transmission) neutron spin echo interferometer in KURRI and JAERI. The number of Larmor precession through these materials gives a phase shift between the trapped ↑ spin wave function of neutron due to the magnetic potential wells and the ↓ spin wave function traveling through non reflecting magnetic layers as a function of the incident angle. These extra spin precessions through multilayer magnetic films are well reproduced by the simulation between the phase difference of ↑ and ↓ spin wave function by solving Schrödinger equation based on one dimensional multi-well potentials. While the observed spin precessions of O-wave through helical magnetic crystal of holmium or ferromagnetic crystal of permalloy at Bragg condition seems proportional to the rocking curve intensity of the magnetic Bragg reflection and different from the predicted one through a magnetic perfect crystal. These results indicate that the multiple Bragg reflection of ↑ spin neutron causes the extra-phase shift while that of the ↓ spin merely path through the crystal without Bragg reflection.