Multiband coupling effect on density of states and tunneling conductance spectra of ferromagnetic material

• The density of states of a two-band ferromagnet were calculated.
• There were crossing points, gaps, change in slope, and energy band extension occurring in the DOS.
• The results show the relationship between DOS and tunneling conductance spectra.

The electronic density of states (DOS) of ferromagnetic materials are theoretically studied within a two-band approach in one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) systems. In the two-band approximation, s-band and d-band coupling were considered. It has been found that if the coupling vanishes, the two bands can cross at some points in the energy spectra. When the coupling between bands is present, a gap is opened up at the corresponding point, thereby avoiding crossovers. The size of the gap depends on the size of the coupling strength. For any dimensionality, the DOS with no coupling behaves like a one-band model. When presenting the coupling strength, there is a change in the slope in the DOS, corresponding to those crossing points. In particular, this change is most prominent when the coupling strength is small and it almost disappears when the coupling strength is strong. With a large coupling strength, the energy band is extended. Finally, the measurable tunneling conductance spectra of a metal/ferromagnet junction within this approximation were clearly analyzed.