A Delicate Balance Between Antiferromagnetism and Ferromagnetism: Theoretical and Experimental Studies of A2MRu5B2 (A = Zr, Hf, M = Fe, Mn) Metal Borides.

A Delicate Balance Between Antiferromagnetism and Ferromagnetism: Theoretical and Experimental Studies of A2MRu5B2 (A = Zr, Hf, M = Fe, Mn) Metal Borides.
Chemistry. 2019 Nov 11;:
Authors: Shankhari P, Bakshi NG, Zhang Y, Stekovic D, Itkis ME, Fokwa BTP
Abstract
Metal-rich borides with the Ti 3 Co 5 B 2 -type structure represent an ideal playground for tuning magnetic interactions through chemical substitutions. In this work, we present density functional theory (DFT) and experimental studies of Ru-rich quaternary borides with the general composition A 2 M Ru 5 B 2 ( A = Zr, Hf, M = Fe, Mn). Total energy calculations show that the phases Zr 2 FeRu 5 B 2 and Hf 2 FeRu 5 B 2 -prefer ground states with strong antiferromagnetic (AFM) interactions between ferromagnetic M -chains. Manganese substitution for iron lowers these antiferromagnetic interchain interactions dramatically and creates a strong competition between FM and AFM states with a slight preference of AFM by Zr 2 MnRu 5 B 2 and of FM by Hf 2 MnRu 5 B 2 . Magnetic property measurements show a field dependence of the AFM transition ( T N ): T N is found at 0.1 T for all phases with predicted AFM states whereas for the predicted FM phase it is found at a much lower magnetic field (0.005 T). Furthermore, T N is lower for the Hf-based phases (20 K and 23 K) if compared to the Zr-based ones (25 K and 28 K), in accordance with DFT prediction of weaker AFM interactions in the Hf-based...

Source: Chemistry - November 10, 2019 Category: Chemistry Authors: Shankhari P, Bakshi NG, Zhang Y, Stekovic D, Itkis ME, Fokwa BTP Tags: Chemistry Source Type: research