Carbon-induced magnetic properties and anomalous Hall effect in Co2Mn2C thin films with L1(0)-like structures

Co2Mn2C thin films were synthesized via vacuum carburization of the host CoMn alloy films based on a conventional gas-solid reaction to demonstrate the effect of C, a common light element, on the magnetic and spintronic materials. The crystal structure transitioned from the disordered face-centered-cubic CoMn to the L10-like Co2Mn2C, for which the lattice constant increased from 0.356 to 0.378 nm. The C 1s x-ray photoemis-sion spectra of the Co2Mn2C film indicated hybridization in C-Co and C-Mn and a homogeneous concentration of C in the film. The enhancement of both the saturation magnetization and the anomalous Hall conductivity (sigma xy) was induced by C, attributing to the magnetic transition to the ferrimagnetic spin order. The surface flatness and high sigma xy are promising characteristics for spintronic applications such as the spin-anomalous Hall effect. The atom-and spin-resolved density of states (DOS) via first-principles calculations revealed that face-centered Mn(II) and Co could be significantly influenced by C because of p-d hybridization, resulting in enhanced spin polarization of the DOS at the Fermi level of similar to 0.82. These results demonstrate that the use of C could be an essential way to boost material properties in the future.