Ba2NiOsO6 : A Dirac-Mott insulator with ferromagnetism near 100 K

Abstract

The ferromagnetic semiconductor Ba2NiOsO6 (Tmag ~100 K) was synthesized at 6 GPa and 1500 C. It crystallizes into a double perovskite structure a = 8.0428 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.3

Re-entrant spin reorientation transition and Griffiths-like phase in antiferromagnetic TbFe0.5Cr0.5O3

“…To consider the strong correlation effects, GGA+U functional with double-counting corrections according to Anisimov et al [27] was used. The chosen values of U were 6 eV for Tb-4 f , 5 eV for Fe-3d, and 3 eV for Cr-3d states, which are comparable to the values found in literature [28][29][30][31][32][33]. Calculations were performed using the lattice parameters obtained from neutron-diffraction data at 7.7 K (see Table I).…”

Insights into cation ordering of double perovskite oxides from machine learning and causal relations

“…In particular, a substantial number of compounds within this family of materials as reported by both theoretical and experimental studies, show multiferroic and polar metallic behavior [3][4][5][6][7]. In AA BB O 6 , the BB sublattices typically order in rock-salt while AA sublattice can order in layered [L], rock-salt [R] or columnar [C] ordering leading to diverse structural, electronic and magnetic properties [8][9][10]. Fixing BB as rock-salt while considering all three possible AA orderings such as AA layered (A[L]B[R]) ordering and AA' rock-salt ordering (A[R]B[R]) lead to non-centrosymmetric space group (P2 1 and Pc, respectively), if (a − a − c + ) distortion is imposed.…”

Electronic, magnetic, optical and thermoelectric properties of Ca2Cr1−xNixOsO6 double perovskites

“…26 In DPs such as Sr 2 CuOsO 6 and Sr 2 NiOsO 6 , a MI state was identied, 27 while HM antiferromagnetism (HMAFM) was predicted in Sr 2 CrOsO 6 and Sr 2 -CrRuO 6 , 1 and for Ba 2 NiOsO 6 , FM with a Dirac-Mott insulating state was observed near 100 K for the bulk material and anomalous quantum Hall behavior was observed on the surface. 28,29 In Sr 2 ScOsO 6 , a transition to AFM was observed at 92 K (ref. 30) and a transition to FiM was observed at 725 K. 31 Similarly, Ca 2 MOsO 6 (where M ¼ Mn, Fe, Co, and Ni) displays a FiM state with Curie temperature (T C ) of 305, 320, 145, and 175 K, respectively.…”