p-Orbital Ferromagnetism Arising from Unconventional O− Ionic State in a New Semiconductor Sr2AlO4 with Insufficiently Bonded Oxygen
【summary】
Oxygen in solids usually exists in an O2− ionic state. As a result, it loses its magnetic nature of a single atom, wherein two unpaired electrons exist in its outer 2p orbitals. Here, we show that an unconventional stable ionic state of O− has been realized in a new semiconductor material Sr2AlO4, leading to an intrinsic p-orbital ferromagnetism stable until ~ 900 K. Experimental and theoretical investigations have clarified that one-fourth of the oxygen atoms in Sr2AlO4 are insufficiently bonded in the crystal structure, resulting in a unique O−-state and p-orbital ferromagnetism. To date, the O− state has been reported to exist only in non-equilibrium conditions, and p-orbital magnetism has been only suggested in impurity bands with small ferromagnetic moments. The present work provides a new route for creating ferromagnetism in semiconductors and exploring new p-orbital physics and chemistry. In addition, the material shows elastic-mechanoluminescence that may enable unprecedented mechano-photonic-spintronics.
【contact】
X.G. Zheng
Professor, Condensed Matter Physics,
Dept. of Physics, Faculty of Science and Engineering,
Saga University
Tel/Fax +81-952-28-8588/+81-952-28-8547