Synergistic doping and stabilization of magnetically tunable LnTi$_3$(Sb,Sn)$_4$ (Ln:Ce--Gd) kagome metals

TL;DR

This study synthesizes and characterizes LnTi3(Sb,Sn)4 kagome metals, revealing how alloying stabilizes their structure and tunes magnetic properties through synergistic doping, with potential for developing customizable intermetallics.

Contribution

It introduces the concept of synergistic doping with (Sb,Sn) to stabilize and tune the magnetic properties of LnTi3(Sb,Sn)4 kagome metals, combining experimental and theoretical approaches.

Findings

(Sb,Sn) alloying stabilizes the structure by adjusting the Fermi level.

Multiple magnetic ground states are tunable via (Sb,Sn) ratio.

The work demonstrates a route for chemical and magnetic property tuning.

Abstract

Here we present our synthesis and characterization of the LnTi$_3$(Sb,Sn)$_4$ (Ln: Ce, Pr, Nd, Sm, Gd) family of cleavable kagome metals. While these materials are isostructural to the LnTi$_3$Bi$_4$ family, they only form as (Sb,Sn) solid-solutions with no corresponding LnTi$_3$Sb$_4$ or LnTi$_3$Sn$_4$ phases. We use a combination of first-principles density functional theory (DFT) and Crystal Orbital Hamilton Population (COHP) calculations to show that (Sb,Sn) alloying has a stabilizing effect on the structure by adjusting the Fermi level, filling bonding states, depopulating antibonding states, and adjusting the density-of-states (DOS) towards local minima, an effect we call ``synergistic doping.'' The tunable Fermi level also has a profound effect on the magnetism, which we demonstrate through a detailed characterization of the SmTi$_3$(Sb,Sn)$_4$ series. The series hosts multiple magnetic ground states resulting from competing magnetic interactions that are tunable by the (Sb,Sn) ratio. While the focus of this work is on SmTi$_3$(Sb,Sn)$_4$, we briefly comment on the (Sb,Sn) solubility range and the conferred magnetic tunability in the other rare-earths compounds (Ln: Ce, Pr, Nd, Gd) as well. Our work demonstrates how the (Sb,Sn) synergistic pair can be used to stabilize the LnTi$_3$(Sb,Sn)$_4$ structure while simultaneously providing a means to tune the magnetism, ultimately providing a potential route to develop new intermetallics with chemical, magnetic, and electronic tunability.