Magnetic Structure of antiferromagnetic Mn₂P₂O₇ at 4.2º K has been established by neutron diffraction from a powder specimen. The magnetic unit cell is found to be the same size as the chemical unit cell. The spins are arranged in ferromagnetic sheets with the moments in each sheet aligned antiferromagnetically relative to its adjacent sheets. Neutron diffraction results in regard to the critical temperature (13±3)º K, and the spine being at an angle of 23º from the a-axis in the a-c plane have been found consistent with the ones obtained by Fowlis, Atkinson, Choh and Stager by susceptibility and NMR studies on the material. However, to confirm the angle with some precision, more work, probably with a single crystal, will be required. / Thesis / Master of Science (MSc)

<p> The magnetic structures of antiferromagnetic manganese pyrophosphate and copper pyrophosphate have been determined by single crystal neutron diffraction techniques. More detailed features of the magnetic structure have been determined by nuclear magnetic resonance (NMR). A discrepancy between previous NMR measurements on Mn2P2o7 and the single crystal neutron measurements was resolved by postulating a low temperature crystallographic phase transition. Information about the dependence of the transferred hyperfine interaction upon the separation of the relevant ions is obtained for Cu2P2o7 from the NMR data and from previously determined deviations from a higher symmetry phase. The origin of the magnetic anisotropy energy in Cu2P2o7 is discussed. </p> / Thesis / Doctor of Philosophy (PhD)