fig4

Figure 4. DFT calculations of CoGd and NCO. (A) Illustration of the Co₇₅Gd₂₅ structure for the DFT calculations; (B) Sketch of the inverse spinel structure of NCO for the DFT calculations; (C) Calculated total DOS, DOS of the Co d states, and DOS of the Gd d and f states in CoGd; (D) Calculated total DOS and DOS of the Co and Ni d states in NCO; The calculated band structures of (E) spin-up and (F) spin-down states of Co and Ni near the Fermi level in NCO; (G) Illustration of the temperature-dependent tunneling behavior when the temperature is below, near, and above T_M. MAO: MgAl₂O₄; NCO: NiCo₂O₄; DFT: density functional theory; TMR: tunneling magnetoresistance; DOS: density of states.