Crystal and Magnetic Structures of Melilite-Type Ba₂MnSi₂O₇

Abstract

Melilite-type Ba2MnSi2O7 was synthesized by a standard powder solid-state reaction route, and its magnetic properties were studied at low temperature. The magnetic structure was found to be C-type pointing along the c axis from neutron powder diffraction, which is different from the G-type ordering previously reported in all other 2-2-4-2 melilites with manganese as the B′-site transition metal. Ab initio (density functional theory) and magnetic dipole–dipole calculations were used to understand the magnetic structure by determining the spin supersuperexchange parameters as well as the relative influence of spin–orbit coupling and the magnetic dipole–dipole interactions.

Momentum-Dependent Spin Splitting by Collinear Antiferromagnetic Ordering

“…Furthermore, there are good AFM candidate materials to show such a symmetric spin-split band structure 39 . For example, orthorhombic compounds, such as Ca 3 Mn 2 O 7 (space group #36 Cmc2 1 ) 40 , Cu 2 V 2 O 7 (space group #43 F dd2) 41 , LaMnO 3 (space group #62 P nma) 42 , NaOsO 3 (space group #62 P nma) 43 , and CaIrO 3 (space group #63 Cmcm) 44 , tetragonal compounds, such as MnLaMnSbO 6 (space group #86 P 4 2 /n) 45 , Ba 2 MnSi 2 O 7 (space group #113 P42 1 m) 46 , Ce 2 Mn 2 Ge 4 O 12 (space group #125 P 4/nbm) 47 , MnF 2 (space group #136 P 4 2 /mnm) 48 , and CoF 2 (space group #136 P 4 2 /mnm) 49 , and trigonal compounds, such as Mn 3 Si 2 Te 6 (space group #163 P31c) 50 , FeBO 3 (space group #167 R3c) 51 , and FeCO 3 (space group #167 R3c) 52 , are almost collinear AFM magnets with the small canted and/or weak ferromagnetic moments, which are expected to exhibit the symmetric spin-split band structures, once the bond multipoles are coupled with the AFM onsite multipoles. Although the effect of the atomic SOC might also contribute to the spin-splitting in the band structure, especially for the materials with heavier elements, it is important to take into account the contribution induced by the effective spin-orbit interaction between kinetic motions of electrons and the AFM mean field at the quantitative level, since the AFM-driven spin-splitting can be the order of the exchange energy.…”

Bennesherite, Ba2Fe2+Si2O7: A new melilite group mineral from the Hatrurim Basin, Negev Desert, Israel

“…Bennesherite has synthetic structural analogs: Ba 2 MgSi 2 O 7 (Shimizu et al 1995), Ba 2 CoSi 2 O 7 (El Bali and Zavalij 2003), Ba 2 CuSi 2 O 7 (Du et al 2003) and Ba 2 MnSi 2 O 7 (Sale et al 2019). Ito and Hafner (1974) also used synthetic Ba 2 Fe 2+ Si 2 O 7 as a standard for Mössbauer measurements of gadolinite spectra.…”

Discovery of Oxygen Carriers by Mining a First-Principle Database

“…Ba is involved in three transitions together with Mn and Si, Similarly to the cases discussed earlier, the first leads to the formation Mn 7 SiO 12 Ba 2 MnSi 2 O 7 , which should be stable up to at least 1200 °C, appear as a reactant in the other two candidates. In addition, both lead to the formation of BaSiO 3 together with the good OCs Mn 2 O 3 and the perovskite BaMnO 3 , respectively.…”