Thermal Expansion of Oxyarsenides (LaO)TAs; T = Transition Metal
We have investigated the precise crystal structure and their temperature dependences of oxyarsenides (LaO)TAs; T = Mn, Fe, Co, as the Fe based superconductor’s parent material family using high energy synchrotron radiation x-ray powder diffraction. Lattice constants a and c decrease with decreasing temperature. Focusing the ratios of the changes normalized by room temperature lattice constants, we have found anisotropic shrinks for the superconductor’s parent material of (LaO)FeAs and the ferromagnetic metal (LaO)CoAs. The shrinkage of the lattice constant c along the stacking direction will be discussed by the temperature dependence of the divided three components of the LaO layer, TAs layer, and the interlayer distance.
J.-L. Bobet, B. Chevalier and D. Fruchart
S. Otsuka et al., "Thermal Expansion of Oxyarsenides (LaO)TAs; T = Transition Metal", Solid State Phenomena, Vol. 170, pp. 131-134, 2011