Flux growth at ambient pressure of millimeter-sized single crystals of LaFeAsO, LaFeAsO1−xFx, and LaFe1−xCoxAsO

J.-Q. Yan, S. Nandi, J. L. Zarestky, W. Tian, A. Kreyssig, B. Jensen, A. Kracher, K. W. Dennis, R. J. McQueeney, A. I. Goldman, R. W. McCallum, T. A. Lograsso
2009 Applied Physics Letters  
Millimeter-sized single crystals of LaFeAsO, LaFeAsO1-xFx, and LaFe1-xCoxAsO were grown in NaAs flux at ambient pressure. The detailed growth procedure and crystal characterizations are reported. The as-grown crystals have typical dimensions of 3 * 4 * 0.05-0.3 mm3 with the crystallographic c-axis perpendicular to the plane of the plate-like single crystals. Some crystals manifest linear dimensions as large as 4-5 mm. X-ray and neutron single crystal scattering confirmed that LaFeAsO crystals
more » ... hibit a structural phase transition at Ts ~ 154 K and a magnetic phase transition at TSDW ~ 140 K. The transition temperatures agree with those determined by anisotropic magnetization, in-plane electrical resistivity and specific heat measurements and are consistent with previous reports on polycrystalline samples. Co and F were successfully introduced into the lattice leading to superconducting LaFe1-xCoxAsO and LaFeAsO1-xFx single crystals, respectively. This growth protocol has been successfully employed to grow single crystals of NdFeAsO. Thus it is expected to be broadly applicable to grow other RMAsO (R = rare earth, M = transition metal) compounds. These large crystals will facilitate the efforts of unraveling the underlying physics of iron pniticide superconductors.
doi:10.1063/1.3268435 fatcat:zry2htakuvhmbitw2d6chppn4u