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  Kumar, R.; Rayaprol, S.; Hoser, A.; Sampathkumaran, E.V.: Canting Angle Behavior of Magnetic Moments in Y-Substituted Tb₂BaNiO₅ and Its Relevance for Magnetoelectric Coupling. Physica Status Solidi B 260 (2023), p. 2300042/1-7

10.1002/pssb.202300042
Open Access Version (externer Anbieter)

Abstract:
The Haldane-spin chain compound, Tb2BaNiO5, has been known to be an exotic multiferroic system, exhibiting antiferromagnetic anomalies at T N1 = 63 K and T N2 = 25 K, with ferroelectricity appearing below T N2 only. Previous reports in addition have established that, interestingly, Tb ions play a direct and decisive role to lead to multiferroic properties with a critical canting angle of magnetic moments, unlike other well-known multiferroics. Herein, the results of temperature-dependent neutron powder diffraction studies on Tb2–x Y x BaNiO5 are reported, to get an insight into the critical canting angle for multiferroic behavior. While multiferroic transition temperature decreases linearly with Y concentration, there is an abrupt drop of relative canting angle (of Tb and Ni magnetic moments) with respect to that in the parent compound for an initial substitution of x = 0.5 in the multiferroic region, without any notable change thereafter. Therefore, it is inferred that this critical canting angle is made up of two components—cooperative (long-range) and local (short-range) contributions.