Pressure-induced metallic ferromagnetism in antiferromagnetic insulator LaMnAsO

Based on the first-principles calculations, we investigate the effects of the hydrostatic pressure on the layered oxypnictide LaMnAsO, and predict that it undergoes a transition from a G-type antiferromagnetic (AFM) insulator to a ferromagnetic (FM) metal at the critical pressure P _c ∼ 18.0 GPa, accompanied by a high-spin state with ( m _Mn = 2.65 μ_B) to low-spin m_Mn = 1.63 μ_B transition, or magnetic moment collapse. Our calculations identify that it is the hydrostatic pressure that collapses the G-type AFM gap, and the large density of state (DOS) around Fermi level stabilizes the FM metallic phase due to the Stoner instability. The pressure-induced AFM insulator to FM metal transition opens up the possibility of two state device applications in the oxypnictide LaMnAsO compound. (paper)