Magnetism in the orthorhombic metal CaFe4As3 was examined through neutron diffraction for powder and single crystalline samples. Incommensurate [qm≈(0.37-0.39)×b*] and predominantly longitudinally (b) modulated order develops through a 2nd order phase transition at TN=89.63(6)K with a 3D Heisenberg-like critical exponent β=0.365(6). A 1st order transition at T2=25.6(9)K is associated with the development of a transverse component, locking qm to 0.375(2)b*, and increasing the moments from 2.1(1) to 2.2(3) μB for Fe2+ and from 1.3(3) to 2.4(4)μB for Fe+. The ab initio Fermi surface is consistent with a nesting instability in cross-linked FeAs strips.
ASJC Scopus subject areas
- Physics and Astronomy(all)