Neutron investigation of the magnetic scattering in an iron-based ferromagnetic superconductor

• Published in: Physical review. B, Condensed matter and materials physics Vol. 92; no. 6
• Main Authors: Lynn, Jeffrey W., Zhou, Xiuquan, Borg, Christopher K. H., Saha, Shanta R., Paglione, Johnpierre, Rodriguez, Efrain E.
• Format: Journal Article
• Language: English
• Published: 31-08-2015
• Subjects: Condensed matter; Diffraction; Ferromagnetic materials; Ferromagnetism; Fluid flow; Scattering; Temperature dependence; Vortices
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.92.060510

Neutron diffraction and small angle scattering experiments have been carried out on the double-isotopic polycrystalline sample ( super(7)Li sub(0.82)Fe sub(0.18) OD)FeSe. Profile refinements of the diffraction data establish the composition and reveal an essentially single phase material with lattice parameters of a = 3.7827 A and c = 9.1277 A at 4 K, in the ferromagnetic-superconductor regime, with a bulk superconducting transition of T sub(C) = 18 K. Small angle neutron scattering measurements in zero applied field reveal the onset of ferromagnetic order below T sub(F) approximately 12.5 K, with a wave vector and temperature dependence consistent with an inhomogeneous ferromagnet of spontaneous vortices or domains in a mixed state. No oscillatory long range ordered magnetic state is observed. Field-dependent measurements establish a separate component of magnetic scattering from the vortex lattice, which occurs at the expected wave vector. The temperature dependence of the vortex scattering does not indicate any contribution from the ferromagnetism, consistent with diffraction data that indicate that the ordered ferromagnetic moment is quite small.