Magnetic excitation of layered Manganites

We propose to perform a single-crystal neutron diffraction study on the layered manganites. Polycrystalline beta-Sr2MnO4 samples studied many years ago were prepared by quenching from high temperatures and were likely off-stoichiometric, affecting both their magnetic behaviour and their electrical transport. We have succeeded in growing single crystals of beta-Sr2MnO4, Sr3Mn2O7 and Sr7Mn4O15 for the first time in a high pressure floating-zone furnace. We will perform neutron diffraction measurements to refine the crystal structure, paying particular attention to the oxygen content, and we will study the antiferromagnetic phase observed below the transition temperatures.