Theoretical Prediction and Experimental Verification of the Chemically Ordered Atomic-Laminate <i>i</i>-MAX Phases (Cr_2/3Sc_1/3)₂GaC and (Mn_2/3Sc_1/3)₂GaC

We combine predictive ab initio calculations with experimental verification of bulk materials synthesis for exploration of new and potentially magnetic atomically laminated i-MAX phases. Two such phases are discovered: (Cr2/3Sc1/3)2GaC and (Mn2/3Sc1/3)2GaC synthesized by the solid state reaction from elemental constituents. The latter compound displays a 2-fold increase in Mn content compared to previously reported bulk MAX phases. Both new compounds exhibit the characteristic in-plane chemical order of Cr(Mn) and Sc, and crystallize in an orthorhombic structure, space group Cmcm, as confirmed by scanning transmission electron microscopy. From density functional theory calculations of the magnetic ground state, including the electron-interaction parameter U, we suggest an antiferromagnetic ground state, close to degenerate with the ferromagnetic state.

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