Biaxial strain effect induced electronic structure alternation and trimeron recombination in Fe(3)O(4)

The Verwey transition in Fe(3)O(4) is the first metal-insulator transition caused by charge ordering. However, the physical mechanism and influence factors of Verwey transition are still debated. Herewith, the strain effects on the electronic structure of low-temperature phase (LTP) Fe(3)O(4) with P2/c and Cc symmetries are investigated by first-principles calculations. LTP Fe(3)O(4) with each space group has a critical strain. With P2/c, Fe(3)O(4) is sensitive to the compressive strain, but it is sensitive to tensile strain for Cc. In the critical region, the band gap of LTP Fe(3)O(4) with both two symmetries linearly increases with strain. When strain exceeds the critical value, DOS of spin-down t(2g) electron at Fe(B4) with P2/c and Fe(B42) with Cc changes between d(x)2(-y)2 and d(xz) + d(yz). The trimerons appear in Cc can be affected by strain. With a compressive strain, the correlation of trimeron along x and y axes is strengthened, but broken along the face diagonal of Fe(B4)O(4), which is opposite at the tensile strains. The results suggest that the electronic structure of Fe(3)O(4) is tunable by strain. The narrower or wider band gap implies a lower or higher transition temperature than its bulk without strains, which also gives a glimpse of the origin of charge-orbital ordering in Fe(3)O(4).