Exotic magnetism and spin-orbit-assisted Mott insulating state in a 3d-5d double perovskite

摘要

The magnetic structure of Ca_2MnReO_6 double perovskite is investigated by neutron powder diffraction and bulk magnetization, showing dominant noncollinear Mn magnetic moments [4.35(7) μ_B] that are orthogonally aligned with the small Re moments [0.22(4) μ_B]. Ab initio electronic structure calculations show that the strong spin-orbit coupling for Re 5d electrons combined with a relatively modest on-site Coulomb repulsion (U_(eff)~(Re) ≥ 0.6 eV) is sufficient to render this material insulating. This is a rare example of spin-orbit-assisted Mott insulator outside the realm of iridates, with remarkable magnetic properties.