Cost density waves (CDWs), a standard phenomenon of periodic lattice distortions, usually suppress ferromagnetism in two-dimensional (2D) supplies, hindering their magnetic purposes. Right here, we report a novel CDWs that generates 2D ferromagnetism as an alternative of suppressing it, by the formation of interstitial anionic electrons as cost modulation mechanism. By way of first-principles calculations and a low-energy efficient mannequin, we discover that the extremely symmetrical monolayer LaBr2 undergoes a 2×1 CDW transition to a magnetic semiconducting T’ section. Concurrently, the delocalized 5d1 electrons of La in LaBr2 redistribute and accumulate throughout the interstitial area within the T’ section, forming anionic electrons, also called 2D electride or electrene. The strongly localized nature of anionic electrons promotes a Mott insulating state and full spin-polarization, whereas the overlap of their prolonged tails yields ferromagnetic direct trade between them. Such transition introduces a brand new magnetic type of CDWs, providing promising alternatives for exploring novel elementary physics and superior spintronics purposes.
