Half-Metallic Ferromagnetism in 2D Janus Monolayers: Mn2GeX (X = As, Sb)

Two-dimensional (2D) Janus materials are a fascinating class of materialsresulting from their unique electronic and magnetic properties induced by mirrorsymmetry breaking. However, 2D Janus materials with intrinsic magnetismremain rather rare, casting a mysterious veil over magnetism. In this work, theelectronic and magnetic properties of Janus Mn2GeX (X=As, Sb) monolayersusing thefirst-principles calculations are investigated. The results demonstratethat these Janus materials exhibit excellent mechanical and dynamic stability,indicating their potential for future applications in nanoscale spintronic devices.Interestingly, the Janus Mn2GeAs and Mn2GeSb monolayers possess excitinghalf-metallic character with wide half-metallic gaps of 0.29 and 0.18 eV, and spingaps of 1.68 and 1.62 eV, respectively. Their calculated ground state exhibits astrong preference for ferromagnetic ordering, with a Curie temperature (T-c)of630 and 590 K, respectively. Additionally, the ferromagnetism of Janus Mn2GeX(X=As, Sb) monolayers is robust against biaxial strain ranging from -6% to 6%.Under 6% tensile strain, the calculatedTcof the Mn2GeSb monolayer is 639 K,which represents a 9% increase compared to theTcobserved in the unstrainedcondition. All these intriguing electronic and magnetic properties make the JanusMn2GeX (X=As, Sb) monolayers an appealing candidate for applications innanoscale spintronic devices