## 3 Result and Discussion
Therefore, the exchange splitting is increased and magnetic moments are increased owing to the truncated periodic crystal field at the interface. The Mn\({}^{\text{A}}\) atom in Mn\({}_{2}\)CoAl bulk displays reverse splitting, which leads to its negative value of magnetic moment, while it converts to normal splitting at the interface, and its magnetic moment obtains a positive value. Quite the opposite, the normal splitting of the Mn\({}^{\text{B}}\) atom in the bulk shifts to reverse splitting at the subinterface of MnCo  
Figure 6: The total density of states (DOS) of various structures. The shadow region indicates the DOS of the Mn\({}_{2}\)CoAl bulk. P stands for spin polarization. and MnMn\({}^{\text{T1}}\) structures. It indicates that the antiferromagnetic interaction of Mn\({}^{\text{A}}\) in bulk turns to a ferromagnetic interaction when it at the interface, while the ferromagnetic coupling of bulk Mn\({}^{\text{B}}\) converts to antiferromagnetic coupling when at the subinterface. Besides, some polarized peaks which have a \(d\)-orbital characteristic appear in the minority spin energy gap at the interface, and the energy of these peaks decreases in the second layer and finally vanishes in the third layer. Therefore, these polarized peaks are considered to be interface states, and they are responsible for the destruction of interface half-metallicity. In addition, it can be seen that the PDOSs of atoms at the third layer are very similar to their features in bulk, revealing that the electronic structures of the deeper layer receive a minor influence of the interface effect. Among various investigated structures, due to the reason that the ISP of the MnCo\({}^{\text{T}}\)-terminated and MnMn\({}^{\text{T1}}\)-terminated interface reaches up to 78% and 45%, respectively; the transport properties of the Mn\({}_{2}\)CoAl/Ag/Mn\({}_{2}\)CoAl spin valve with an MnCo\({}^{\text{T}}\)-terminated and MnMn\({}^{\text{T1}}\)-terminated interface have been calculated. The energy- and spin-resolved transmission coefficient \(T^{\sigma}(E)\) is defined as  
Figure 2:0  
where \(n^{2}\) represents the number of sampling points in the two-dimensional Brillouin zone (2-D BZ), and \(\sigma\) is the spin direction. The transmission coefficients of the Mn\({}_{2}\)CoAl/Ag/Mn\({}_{2}\)CoAl junction with an MnCo\({}^{\text{T}}\)-terminated and MnMn\({}^{\text{T1}}\)-terminated interface at equilibrium are calculated and presented in Figure 8, and the Fermi level has an energy of zero. When magnetic moments of two Mn\({}_{2}\)CoAl electrode layers are in a parallel configuration (PC), the transmission coefficient curve of the majority spin channel is totally different to that of the minority spin channel. For the MnCo\({}^{\text{T}}\)-terminated structure, the value of the transmission coefficient of the majority spin channel at Fermi level \(T_{PC}^{maj}(E_{f})\) is 0.00663, and that of the minority spin channel at Fermi level \(T_{PC}^{\text{min}}(E_{f})\) is almost zero. For the MnMn\({}^{\text{T1}}\)-terminated structure, \(T_{PC}^{maj}(E_{f})\) is 0.0038 and \(T_{PC}^{\text{min}}(E_{f})\) is also close to zero. When the magnetic moments of two Mn\({}_{2}\)CoAl electrode layers are in an anti-parallel configuration (APC),  
Figure 2:1 The partial density of states (PDOS) of (**a**) MnCo\({}^{\text{T}}\)- and (**b**) MnMn\({}^{\text{T1}}\)-terminated structures. The shadow region indicates atomic PDOS of the bulk. L1, L2, and L3 indicate the interface, subinterface, and next subinterface, respectively. due to the reason that our Mn\({}_{2}\)CoAl/Ag/Mn\({}_{2}\)CoAl spin valve model is geometrically symmetric with respect to the middle plane of the center scattering region, the transmission coefficient curve of the spin up channel is exactly the same as that of the spin down channel. For the MnCo\({}^{\text{T}}\)-terminated structure, the value of the transmission coefficient of the majority spin channel and minority spin channel at the Fermi level is \(T_{APC}^{maj}(E_{f})=T_{APC}^{\text{min}}(E_{f})=0.111\times 10^{-3}\).