Charge rearrangement in magnetite: from magnetic field induced easy axis switching to femtoseconds electronic processes

Abstract

Magnetite is the oldest magnet and the first material where the concept of a strong correlations driven metal–insulator transition was suggested and found at T_V = 124 K in the so-called Verwey phase transformation. Recently, the structure below T_V was solved revealing subtle electronic structure in the form of trimeron lattice that, according to yet another recent communication, may be switched within femtosecond range. In this review article, we argue that the same change of trimeron lattice can be achieved by a magnetic field, in the phenomenon called the easy axis switching. The results of many of our experiments show that although this process is best viewed by magnetization studies, it is also reflected in magnetostriction, causes some changes in electronic transport and can be observed microscopically by NMR that proved electronic order alteration. All those facts suggest that the axis switching process observed and studied by us is intimately linked with the fast change of electronic trimeron order mentioned above.

Keywords:

• metal–insulator phase transition
• magnetite
• charge order
• orbital order
• strongly correlated systems

Acknowledgement

The authors are grateful to J.M. Honig for providing magnetite single crystals and to C. Kapusta for his help in the experiment.

Additional information

Funding

This work was financially supported by the Ministry of Science and Higher Education (MNiSW).