Metallic nature and site-selective magnetic moment collapse in iron oxide Fe4O5 at the extreme conditions of Earth's deep interior

Electronic properties of single-crystalline Fe4O5

“…To date, band structure calculations have been inconsistent in the prediction of the electronic properties of Fe 4 O 5 , reporting it to be a metal, 49,101 a wide-gap semiconductor, 50 or to be a narrow-gap semiconductor with E g = 0.2 eV. 102 Our study resolves these discrepancies.…”

“…99 However, the above small difference in the energies of the lowermost d-orbitals of Fe1, Fe2, and Fe3 atoms in Fe 4 O 5 is challenging to trace both experimentally and by band structure calculations. 100 To date, band structure calculations have been inconsistent in the prediction of the electronic properties of Fe 4 O 5 , reporting it to be a metal, 49,101 a wide-gap semiconductor, 50 or to be a narrow-gap semiconductor with E g = 0.2 eV. 102 Our study resolves these discrepancies.…”

“…4b) well explains the non-zero density of states at the Fermi level. 49,101 Whereas, due to the low carrier mobility (Fig. 4c), its electrical conductivity indeed may look as semiconducting.…”

“…46,47 To date, the electronic properties of Fe 4 O 5 have been controversially reported in the literature. While band structure calculations predicted a metallic nature of both Fe 4 O 5 48 and Fe 5 O 6 , 49 recent experiments showed seemingly semiconducting properties of Fe 4 O 5 and its metallization was observed only under high pressure above 80 GPa at room temperature. 50,51 A typical splitting of the d-orbitals of Fe 2+ (3d 6 ) and Fe 3+ (3d 5 ) ions in highly-symmetric octahedral and trigonal-prismatic oxygen coordinations 52,53 is depicted in Fig.…”

Orthogonal magnetic structures of Fe4O5: representation analysis and DFT calculations

“…Since the discovery of novel high-pressure iron oxides, their crystal chemistry and physical properties have been of great interest. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Based on the common packing motif, these compounds constitute a homologous series nFeO•mFe 2 O 3 , containing η-Fe 2 O 3 , HP-Fe 3 O 4 , Fe 4 O 5 , Fe 5 O 6 , Fe 5 O 7 , etc. 4 Their crystal structures consist of two main building blocks, namely the slabs of edge-shared Fe-O octahedra separated by arrays of one-dimensional (1D) chains of Fe ions coordinated by a trigonal prism (see Fig.…”