Abstract
The ferromagnetic semiconductor Ba2NiOsO6 (Tmag ~100 K) was synthesized at 6 GPa and
1500 ï‚°C. It crystallizes into a double perovskite structure [Fm-3m; a = 8.0428(1) Ã…], where the Ni2+ and
Os6+ ions are perfectly ordered at the perovskite B-site. We show that the spin-orbit coupling of Os6+
plays an essential role in opening the charge gap. The magnetic state was investigated by density
functional theory calculations and powder neutron diffraction. The latter revealed a collinear
ferromagnetic order in a >21 kOe magnetic field at 5 K. The ferromagnetic gapped state is
fundamentally different from that of known dilute magnetic semiconductors such as (Ga,Mn)As and
(Cd,Mn)Te (Tmag < 180 K), the spin-gapless semiconductor Mn2CoAl (Tmag ~720 K), and the
ferromagnetic insulators EuO (Tmag ~70 K) and Bi3Cr3O11 (Tmag ~220 K). It is also qualitatively different
from known ferrimagnetic insulator/semiconductors, which are characterized by an antiparallel spin
arrangement. Our finding of the ferromagnetic semiconductivity of Ba2NiOsO6 should increase interest
in the platinum group oxides, because this new class of materials should be useful in the development of
spintronic, quantum magnetic, and related devices
