Phase Separation in A-site Ordered Perovskite Manganite LaBaMn2_2O6_6 Probed by 139^{139}La and 55^{55}Mn NMR

$^{139}$La- and $^{55}$Mn-NMR spectra demonstrate that the ground state of the A-site ordered perovskite manganite LaBaMn$_2$O$_6$ is a spatial mixture of the ferromagnetic (FM) and antiferromagnetic (AFI(CE)) regions, which are assigned to the metallic and the insulating charge ordered state, respectively. This exotic coexisting state appears below 200 K via a first-order-like formation of the AFI(CE) state inside the FM one. Mn spin-spin relaxation rate indicates that the FM region coexisting with the AFI(CE) one in LaBaMn$_2$O$_6$ is identical to the bulk FM phase of the disordered form La$_{0.5}$Ba$_{0.5}$MnO$_3$ in spite of the absence of A-site disorder. This suggests mesoscopic rather than nanoscopic nature of FM region in LaBaMn$_2$O$_6$\@.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let

Magnetic structure and phase transitions of Co1−xMnxCl2⋅2H2O\mathrm{Co_{1-x}Mn_xCl_2 \cdot 2H_2O} and C1−xMnxCl2⋅2D2O\mathrm{C_{1-x}Mn_xCl_2 \cdot 2D_2O}

We present neutron diffraction results of the magnetic structure, phase transitions and magnetic short-range order of Co1-xMnxCl2 · 2H2O/D2O single crystals. For samples in an intermediate composition range, where a spin glass phase exists, we found the coexistence of spin glass and long-range antiferromagnetic order