Ultra-thin structures of manganese fluorides: conversion from manganese dichalcogenides by fluorination

In this study, it is predicted by density functional theory calculations that graphene-like novel ultra-thin phases of manganese fluoride crystals, that have nonlayered structures in their bulk form, can be stabilized by fluorination of manganese dichalcogenide crystals. First, it is shown that substitution of fluorine atoms with chalcogens in the manganese dichalcogenide host lattice is favorable. Among possible crystal formations, three stable ultra-thin structures of manganese fluoride, 1H-MnF 2 , 1T-MnF 2 and MnF 3 , are found to be stable by total energy optimization calculations. In addition, phonon calculations and Raman activity analysis reveal that predicted novel single-layers are dynamically stable crystal structures displaying distinctive characteristic peaks in their vibrational spectrum enabling experimental determination of the corresponding phases. Differing from 1H-MnF 2 antiferromagnetic (AFM) large gap semiconductor, 1T-MnF 2 and MnF 3 single-layers are semiconductors with ferromagnetic (FM) ground state. Growth of ultra-thin magnetic manganese fluoride crystals by fluorination of manganese dichalcogenides and resulting structural, magnetic, vibrational, mechanical, and electronic properties are investigated theoretically.