R11Ni4In9 (R = rare earth) compounds exhibit an unusual self-assembled nano/microfibrous morphology that results in anisotropic structural and magnetic behaviors. The existence of new compounds for R = Dy, Ho, Er, Tm and Lu, has been established (orthorhombic Nd(11)Pd(4)In(9)type, oC48, Cmmm, Z = 2), showing that the formation of these phases, previously known for R = La-Nd, Sm, Gd, Tb and Y, extends to all of the rare earth elements, except Sc, Eu and Yb. The results of physical property measurements performed on oriented fibers of Tb11Ni4In9, Dy11Ni4In9 and Y11Ni4In9 are presented. Multiple magnetic transitions are observed in Tb11Ni4In9 and Dy11Ni4In9 with the highest ordering temperature, T-C, of 112 and 88 K, respectively. Y11Ni4In9 is a Pauli paramagnet down to 2 K. The fibrous microstructure of these compounds leads to a strong anisotropy in their electrical resistivity and magnetization behaviors. The c-axis of the orthorhombic cell is the easy magnetization and high electrical-conductivity direction. Ferrimagnetic-like behavior, with extremely high coercive fields (H-C = 6.6 T for Tb11Ni4In9 at 5K and H-C = 5.7 T for Dy11Ni4In9 at 2 K), is found when the fibers (and the c-axis) are oriented parallel to the magnetic field direction; antiferromagnetic-like ground state is observed with the fibers oriented orthogonal (i.e., in the a-b plane). Appearance of a Griffiths phase regime is observed in both compounds before entering the ordered magnetic states. This is more evident for fibers orthogonal to the magnetic field and is even preserved at 1 T. Field induced spin-flop magnetic transitions are also observed in Tb11Ni4In9 and Dy11Ni4In9 with fibers orthogonal and parallel to the field, respectively. First principles calculations have been performed for several representative compounds to explain the underlying phase stability and their magnetism. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
The nano-microfibrous R11Ni4In9 intermetallics: New compounds and extraordinary anisotropy in Tb11Ni4In9 and Dy11Ni4In9
Provino A;Ferdeghini C;Manfrinetti P;
2015
Abstract
R11Ni4In9 (R = rare earth) compounds exhibit an unusual self-assembled nano/microfibrous morphology that results in anisotropic structural and magnetic behaviors. The existence of new compounds for R = Dy, Ho, Er, Tm and Lu, has been established (orthorhombic Nd(11)Pd(4)In(9)type, oC48, Cmmm, Z = 2), showing that the formation of these phases, previously known for R = La-Nd, Sm, Gd, Tb and Y, extends to all of the rare earth elements, except Sc, Eu and Yb. The results of physical property measurements performed on oriented fibers of Tb11Ni4In9, Dy11Ni4In9 and Y11Ni4In9 are presented. Multiple magnetic transitions are observed in Tb11Ni4In9 and Dy11Ni4In9 with the highest ordering temperature, T-C, of 112 and 88 K, respectively. Y11Ni4In9 is a Pauli paramagnet down to 2 K. The fibrous microstructure of these compounds leads to a strong anisotropy in their electrical resistivity and magnetization behaviors. The c-axis of the orthorhombic cell is the easy magnetization and high electrical-conductivity direction. Ferrimagnetic-like behavior, with extremely high coercive fields (H-C = 6.6 T for Tb11Ni4In9 at 5K and H-C = 5.7 T for Dy11Ni4In9 at 2 K), is found when the fibers (and the c-axis) are oriented parallel to the magnetic field direction; antiferromagnetic-like ground state is observed with the fibers oriented orthogonal (i.e., in the a-b plane). Appearance of a Griffiths phase regime is observed in both compounds before entering the ordered magnetic states. This is more evident for fibers orthogonal to the magnetic field and is even preserved at 1 T. Field induced spin-flop magnetic transitions are also observed in Tb11Ni4In9 and Dy11Ni4In9 with fibers orthogonal and parallel to the field, respectively. First principles calculations have been performed for several representative compounds to explain the underlying phase stability and their magnetism. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
