ABSTRACT
In order to make a new approach to the elucidation of the microscopic mechanisms of multiferroicity in the RMn2O5 family, experiments with different methods of polarized neutrons scattering were performed on a TbMn2O5 single crystal. We employed three different techniques of polarized neutron diffraction without the analysis after scattering, the XYZ-polarization analysis, and technique of spherical neutron polarimetry (SNP). Measurements with SNP were undertaken both with and without external electric field. A characteristic difference in the population of 'right' and 'left' helix domains in all magnetically ordered phases of TbMn2O5, was observed. This difference can be controlled by an external electric field in the field-cooled mode. The analysis of the results gives an evidence that antisymmetric Dzyaloshinsky-Moria exchange is effective in all the magnetic phases in TbMn2O5.
ABSTRACT
Two aspects of the ambient pressure magnetic structure of heavy fermion material CeRhIn5 have remained under some debate since its discovery: whether the structure is indeed an incommensurate helix or a spin density wave, and what is the precise magnitude of the ordered magnetic moment. By using a single crystal sample optimized for hot neutrons to minimize neutron absorption by Rh and In, here we report an ordered moment of [Formula: see text]. In addition, by using spherical neutron polarimetry measurements on a similar single crystal sample, we have confirmed the helical nature of the magnetic structure, and identified a single chiral domain.
ABSTRACT
A new polarized neutron single crystal diffractometer POLI (Polarization Investigator) has been developed at the Maier-Leibnitz Zentrum, Garching, Germany. After reviewing existing devices, spherical neutron polarimetry has been implemented on POLI as a main experimental technique using a third-generation cryogenic polarization analysis device (Cryopad) built in cooperation between RWTH University and Institut Laue-Langevin. In this report we describe the realization and present the performance of the new Cryopad on POLI. Some improvements in the construction as well as details regarding calibrations of Cryopad and its practical use are discussed. The reliable operation of the new Cryopad on POLI is also demonstrated.
ABSTRACT
The control of multiferroic domains through external electric fields has been studied by dielectric measurements and by polarized neutron diffraction on single-crystalline TbMnO3. Full hysteresis cycles were recorded by varying an external field of the order of several kV mm(-1) and by recording the chiral magnetic scattering as well as the charge in a sample capacitor. Both methods yield comparable coercive fields that increase upon cooling.
