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 (M 1 2/3 M 2 1/3 ) 2 AC chemistry, where the M 1 and M 2 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 2/3 RE 1/3 ) 2 AlC, and the rare-earth, RE, elements are Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. 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.