Magnetic properties and structures of fibrous R$_{11}$Ni$_{4}$In$_{9}$ intermetallics (R $=$ heavy rare earths)

The existence and the unusual self-assembled nano/microfibrous morphology of the R$_{11}$T$_{4}$In$_{9}$ (R $=$ rare earth, T $=$ Ni, Pd, Pt) phases has been recently studied [1,2,3]. All the rare earths (but Sc, Eu, Yb) form this ternary compound (orthorhombic Nd$_{11}$Pd$_{4}$In$_{9}$-type, \textit{oC}48, \textit{Cmmm}). The bundles of fibers grow parallel to the temperature gradient and along the short $c$-axis. In this presentation we describe the results of a detailed investigation of the physical properties (electrical resistivity, heat capacity, magnetization measurements) of Tb$_{11}$Ni$_{4}$In$_{9}$, Dy$_{11}$Ni$_{4}$In$_{9}$ and Ho$_{11}$Ni$_{4}$In$_{9}$ by orienting the fibers parallel and orthogonal, respectively, to the electric current and magnetic field. The unusual fibrous microstructure of these compounds leads to a strong anisotropy in their physical properties, with the $c$-axis of the orthorhombic cell being the easy magnetization and high electrical-conductivity direction. The magnetic structures of Tb$_{11}$Ni$_{4}$In$_{9}$ and Ho$_{11}$Ni$_{4}$In$_{9}$, which have multiple magnetic orderings, have been investigated by neutron diffraction. The complex magnetic behavior found in these phases is a result of the competing ferrimagnetic (along the $c$-axis) and antiferromagnetic (on the $a-b$ plane) orderings of the five R sublattices.