Physical properties and crystal structure analysis of double-perovskite NdBaMn2O6 by using single crystals

We have succeeded in growing large single crystals of double-perovskite ${\mathrm{NdBaMn}}_{2}{\mathrm{O}}_{6}$ with the $c$ axis aligned, and carried out a crystal structure analysis and measurements of resistivity and magnetization. A first-order metal-insulator transition at ${T}_{MI}\ensuremath{\simeq}290$ K is accompanied by a large jump of magnetization and lattice constants. The distortion of ${\mathrm{MnO}}_{6}$ octahedra is consistent with a ferroic orbital order of ${x}^{2}\ensuremath{-}{y}^{2}$ type, although other orbital orders cannot be completely discarded. N\'eel temperature ${T}_{N}$ is determined to be 235 K, which is fairly lower than ${T}_{MI}$, on the basis of the onset of a large magnetic anisotropy. Another structural phase transition from tetragonal to orthorhombic is found at 370 K, which arises from staggered tilting of ${\mathrm{MnO}}_{6}$ octahedra and little affects the transport and magnetic properties.