Atomically Layered and Ordered Rare-Earth i-MAX Phases: A New Class of Magnetic Quaternary Compounds

In 2017, we discovered quaternary i-MAX phases—atomically layered solids, where M is an early transition metal, A is an A group element, and X is C—with a (M¹_2/3M²_1/3)₂AC chemistry, where the M¹ and M² atoms are in-plane ordered. Herein, we report the discovery of a class of magnetic i-MAX phases in which bilayers of a quasi-2D magnetic frustrated triangular lattice overlay a Mo honeycomb arrangement and an Al Kagomé lattice. The chemistry of this family is (Mo_2/3RE_1/3)₂AlC, and the rare-earth, RE, elements are Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. Here, the magnetic properties were characterized and found to display a plethora of ground states, resulting from an interplay of competing magnetic interactions in the presence of magnetocrystalline anisotropy.