Synthesis, structure, and magnetism in the ferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>MnAs</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math>: Well-separated spin chains coupled via itinerant electrons

Abstract

In this work, we systematically report the synthesis, structure, and magnetism of a compound of filled anti-${\mathrm{Mn}}_{3}{\mathrm{Si}}_{5}$ type ${\mathrm{La}}_{3}{\mathrm{MnAs}}_{5}$. It crystallizes in a hexagonal structure with the space group of $P{6}_{3}/mcm$ (193). The structure consists of face-sharing ${\mathrm{MnAs}}_{6}$ octahedral chains along the $c$ axis, which are well separated by a large distance of 8.$9913\phantom{\rule{0.28em}{0ex}}\AA{}$, demonstrating a strong one-dimensional (1D) structural character. Physical property measurements indicate that ${\mathrm{La}}_{3}{\mathrm{MnAs}}_{5}$ is a ferromagnetic metal with ${T}_{\mathrm{C}}\ensuremath{\sim}112\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Due to the short-range intrachain spin coupling, the susceptibility deviates from the Curie-Weiss behavior in a wide temperature window and the magnetic entropy corresponding to the ferromagnetic transition is significantly lower than that expected from the fully saturated state. The magnetic critical behavior studies show that ${\mathrm{La}}_{3}{\mathrm{MnAs}}_{5}$ can be described by the three-dimensional Heisenberg model. The orbital hybridization between the 1D ${\mathrm{MnAs}}_{6}$ chain and intermediate La atom near the Fermi level reveals that the itinerant electrons play a key role in transmitting spin interaction among the ${\mathrm{MnAs}}_{6}$ spin chains. Our results indicate that ${\mathrm{La}}_{3}{\mathrm{MnAs}}_{5}$ is a rare ferromagnetic metal with well-separated spin chains, which provides a good opportunity to study the mechanism of interchain spin coupling via itinerant electrons.

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