Magnetic correlations in small particle systems, studied with the neutron depolarization technique

Neutron depolarization (ND) theory for particulate media is discussed. An ND experiment yields a correlation matrix, ω, describing the micromagnetic state of the medium. The relations between ω and parameters describing the individual particles, particle interactions, orientational correlations between particles, and density variations within the medium are discussed. It is concluded that with these relations the ND technique can successfully be used to study the micromagnetic state of particulate media. The matrix ω can yield quantitative information about the individual particles and several types of superdomains. The theory is applied to the results of ND measurements on CrO₂-powder