Isotropic ME effect was observed in multiferroic Tb_1-xGd_xMn₂O₅, where electric polarization reappears along the b axis as a response to application of a magnetic field along each crystallographic axis. This isotropic ME effect is distinct from those observed in other RMn₂O₅ and multiferroic materials. Employing resonant X-ray scattering, we revealed that the isotropic ME effect is attributed to competition between two different magnetic ordering. In addition, measurement of oxygen spin polarization under magnetic field suggests that charge transfer between Mn and O ions have microscopic contribution to the ME effect.

Using small-angle neutron scattering (SANS), we investigate a deformation of the magnetic skyrmion lattice in the bulk single-crystalline MnSi under electric current flow. A significant broadening of the skyrmion-lattice-reflection peaks was observed in the SANS pattern for current densities greater than a threshold value j_t ~ 10⁶ A/m². We show this peak broadening to originate from a spatially inhomogeneous rotation of the skyrmion lattice, with an inverse rotation sense observed for opposite sample edges aligned with the direction of current flow. The peak broadening and the corresponding skyrmion lattice rotations remain finite even after switching off the electric current. These results indicate that skyrmion lattices under current flow experience significant friction near the sample edges, and plastic deformation due to pinning effects.

In this article, the novel neutron technique, white neutron holography, is introduced. White neutron holography is an indispensable probe for local atomic structures around dopants in functional materials. The advantages, brief principle, and recent results are explained. We believe that white neutron holography will be a novel probe which characterizes materials science in J-PARC.

Present status of European Spallation Source and its expected performance with a general comparison between the typical spectrometers at ESS and those in J-PARC are presented. The article also tries to show the advantages and disadvantages of the very different source characters between the two, and to make some suggestions for improvement to extract the full potential from them in the future.

Spin fluctuations are widely believed to play an important role in the superconducting mechanisms of unconventional high-temperature superconductors, and they have been observed in various iron-based superconductors so far. However, in LaFePO_0.9, they have not been observed by inelastic neutron scattering. LaFePO_0.9 is an iron-based superconductor with a low superconducting transition temperature (T_c = 5 K), where line nodes are observed in the superconducting order parameter. The line-node symmetry typically originates from sign reversal of the order parameter in spin-fluctuation-mediated superconductivity. This contradiction has been a longstanding mystery of this superconductor. Here, we report spin fluctuations were found at high energies such as 30-50 meV. The line-node symmetry can be explained naturally as spin-fluctuation-mediated superconductivity.