Strain-induced phase transition in β-MnO₂

¹ College of Science, Nanjing University of Aeronautics and Astronautics - Nanjing, 210016, China
² School of Mathematics and Physics, Nanjing University of Information Science and Technology Nanjing, 210044, China
³ School of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications Nanjing, 210046, China
⁴ Department of Physics, University of Connecticut - Storrs, CT 06269, USA

^(a) xhyan@nuaa.edu.cn

Received: 21 June 2012
Accepted: 28 June 2012

Abstract

The phase transition of β-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.