A joint research team consisting of NIMS, JAEA and the Institut Laue Langevin has developed a high-pressure cell composed of completely nonmagnetic materials. The team then succeeded for the first time in analyzing neutron polarization in three dimensions at an extremely high pressure of several gigapascals using the cell. This technique is applicable to detailed analysis of electron spin arrangements. The team also discovered a material with potential as a next-generation PC memory material due to the multiferroic properties it exhibited under high pressure. The technique may be used to understand pressure-induced changes in electron spin arrangements in various materials and to develop new materials by controlling spins.