Enhanced survival of short-range magnetic correlations and frustrated interactions in R3TR3T intermetallics

Elastic and inelastic neutron scattering and magnetization measurements have been used to study peculiarities of the magnetic state in R3TR3T compounds (R=Gd, Er, Tb; T=Ni, Co) below and above magnetic ordering temperatures. A pronounced non-Brillouin shape of the magnetization curves observed in the antiferromagnetic compounds Gd3Ni and Tb3Ni above their magnetic ordering temperatures together with earlier reported data about the retention of the magnetic contribution to the total specific heat of Gd3T and anomalous behavior of the electrical resistivity above magnetic ordering temperatures are ascribed to the existence of short-range magnetic correlations in the wide temperature range in the paramagnetic state. The persistence of short-range magnetic order up to temperatures greater than 5–6 times the Néel temperature has been revealed by powder neutron diffraction measurements performed for Tb3Ni and Tb3Co. On the other hand, results from inelastic neutron scattering show that the low temperature magnetic excitations are strongly suppressed in both Tb3Co and Er3Co. It is suggested that the extended short-range magnetic correlations, which turn out to be an inherent feature of R3TR3T type compounds, are due to the layered crystal structure and to the difference between geometrically frustrated intra-layer exchange interactions and inter-layer exchange.

► We studied the magnetic state of R3T compounds (R=Gd, Er, Tb; T=Ni, Co).
► They show complicated magnetic behavior below and above magnetic ordering temperatures.
► Our neutron diffraction study has revealed short-range magnetic correlations above TN.
► Short-range correlations are found to persist up to temperatures higher than (5-6) TN.
► The physical properties of R3T are strongly affected by these short-range correlations.