Strain-induced phase transition in β-MnO2

The phase transition of beta-MnO2 under negative pressure and external strain was investigated via the density function theory. During the expansion, the half-metallic phase appeared. Using the Heisenberg model, the variations in the exchange integrals between Mn4+ pairs were determined. A crossover between the dominate exchange integrals occurred, which resulted in the formation of the ferromagnetic phase. On the other hand, the double exchange mechanism and weakening of the crystal field were the two reasons for the formation of the majority of conduction bands. Copyright (C) EPLA, 2012