Nuclear Resonant Small-Angle Scattering for Investigation of Microstructures in Electronic States

The measurement of the nuclear resonant small-angle scattering was achieved by scanning the position of a multi-element avalanche photodiode detector, detecting delayed nuclear resonant signal to investigate microstructures of the electronic states. The nuclear resonant small-angle scattering has been attempted to study the coexisting phase of superconductivity and magnetic order in an under-doped Fe-based superconductor, BaosKo2Fe2As2. Clear change was not observed in the exponent of the angular profile of the nuclear resonant small angle scattering in the coexisting temperature. This fact implies the microstructure in the coexisting phase does not have an obvious typical scale but a complex spatial texture. Another attempt was perfouned for the microstructure in the magnetic properties in an anti-invar fcc Fe-Ni-C alloy to investigate mechanism of the anti-invar properties. An enhancement of the angular profile in a few tens of nm range was observed as decreasing the temperature down to a little below the Curie temperature. This fact implies the existence of the inhomogeneity of magnetically-ordered phase in this range of size, which may related to the anti-invar properties.