Magnetic optimization and regulation mechanism of La2CoMnO6 double-perovskite ceramics by Ti-doping at Mn-site

This work focuses on the magnetic optimization of La2CoMnO6 (LCMO) double-perovskite ceramics by Ti-doping at Mn-site. LCMO ceramics with different Ti-doping contents (LCMTxO, x = 0.1–0.4) were prepared by plasma activated sintering, and the effect of Ti-doping on the structural and magnetic properties of the ceramics is studied systematically. All the ceramics exhibit dense structure and small grain size, with a monoclinic P21/n crystalline structure. With the increasing of Ti-doping content, the proportions of Co2+ and Mn4+ in the LCMTxO ceramics change accordingly, reaching the highest values at x = 0.1. Since the Co2+-O-Mn4+ ferromagnetic super-exchange is the dominant factor affecting the magnetic properties of the LCMTxO ceramics, it is reasonable that a high saturation magnetization (Ms = 4.58μB/f.u) is obtained for the LCMT0.1O ceramic. The effect of Ti-doping on the orbital structure and magnetic regulation of the LCMTxO double-perovskite ceramics is further investigated by the first-principle calculation. It is found that the magnetic moments of Co and Mn ions will increase by the appropriate addition of Ti, which makes most Co ions exist in the form of Co2+, underpinning the La2Co2+Mn4+O6 ferromagnetic state and improving the magnetic properties.