Magnetic anisotropy and reduced neodymium magnetic moments in Nd3Ru4Al12.

This paper addresses the electronic properties of Nd3Ru4Al12 (hexagonal crystal structure) with focus on its magnetic anisotropy that allows a comparison between single-ion and two-ion mechanisms when comparing to U3Ru4Al12. We performed magnetization measurements on a single crystal in static and pulsed magnetic fields as well as neutron-diffraction experiments. Nd3Ru4Al12 is a strongly anisotropic uniaxial ferromagnet with a Curie temperature of 39 K. The magnetic moments are aligned collinearly along the [001] axis. The magnetic structure of Nd3Ru4Al12 has orthorhombic symmetry for which the crystallographic Nd site is split into two magnetically inequivalent positions, Nd1 and Nd2. The Nd1 and Nd2 atoms exhibit reduced magnetic moments, 0.95 and 2.66 μB, as compared to the free Nd3+ -ion value (3.28 μB). We discuss this finding in terms of crystal-field effects and competing exchange and anisotropy interactions. Since the single-ion mechanism in Nd3Ru4Al12 leads to uniaxial anisotropy and the two-ion mechanism of the actinide analog U3Ru4Al12 is known to lead to planar anisotropy, this paper demonstrates the decisive influence of these different mechanisms on the magnetic anisotropy. [ABSTRACT FROM AUTHOR]