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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LaMnSbO by Materials Project

LaMnSbO is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. La3+ is bonded in a 4-coordinate geometry to four equivalent Sb3- and four equivalent O2- atoms. All La–Sb bond lengths are 3.61 Å. All La–O bond lengths are 2.43 Å. Mn2+ is bonded to four equivalent Sb3- atoms to form a mixture of edge and corner-sharing MnSb4 tetrahedra. All Mn–Sb bond lengths are 2.84 Å. Sb3- is bonded in a 8-coordinate geometry to four equivalent La3+ and four equivalent Mn2+ atoms. O2- is bonded to four equivalent La3+ atoms to form a mixture of distorted edge and corner-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Spin dynamics in antiferromagnetic oxypnictides and fluoropnictides: LaMnAsO, LaMnSbO, and BaMnAsF

In this study, inelastic neutron scattering (INS) from polycrystalline antiferromagnetic LaMnAsO, LaMnSbO, and BaMnAsF are analyzed using a J 1 - J 2 - J c Heisenberg model in the framework of the linear spin-wave theory. All three systems show clear evidence that the nearest- and next-nearest-neighbor interactions within the Mn square lattice layer ( J 1 and J 2 ) are both antiferromagnetic (AFM). However, for all compounds studied the competing interactions have a ratio of 2 J 2 / J 1 < 1 , which favors the square lattice checkerboard AFM structure over the stripe AFM structure. The interplane coupling J c in all three systems is on the order of ~ 3 × 10 - 4 J 1 , rendering the magnetic properties of these systems with quasi-two-dimensional character. The substitution of Sb for As significantly lowers the in-plane exchange coupling, which is also reflected in the decrease of the Néel temperature, T N . Although BaMnAsF shares the same MnAs sheets as LaMnAsO, their J 1 and J 2 values are substantially different. Lastly, using density functional theory, we calculate exchange parameters J i j to rationalize the differences among these systems.

36 MATERIALS SCIENCE↗