The exploration of high-performance tunnel barrier materials is a key scientific issue for enhancing the performance of magnetic tunnel junctions (MTJs) devices and advancing the development of spintronics. In recent years, two-dimensional van der Waals materials have attracted extensive attention in tunnel barrier studies because of their atomically flat interfaces, reduced interfacial scattering, and excellent capability for heterogeneous integration. In comparison with two-dimensional systems, however, onedimensional magnetic semiconductors exhibit more pronounced quantum confinement effects and superior spin tunability, thereby offering unique advantages for achieving efficient spin filtering and enhancing spindependent transport responses. These characteristics provide a promising new avenue for the construction of novel low-dimensional spintronic devices. Motivated by these considerations, we propose a new MTJs architecture employing a one-dimensional MoI₃ atomic chain as the tunnel barrier layer. By combining first-principles calculations with the nonequilibrium Green’s function method, we systematically investigate the spin-dependent transport properties of this device under different scattering-region lengths and external bias voltages. Through analyses of the current-voltage characteristics, transmission spectra, and spinpolarized transport behavior, the microscopic physical mechanisms underlying its high-performance magnetotransport response are elucidated. The results show that MTJs based on one-dimensional MoI₃ atomic chains exhibit excellent spin transport characteristics for different scatteringregion lengths. Within the low-bias regime, the device can achieve an ultrahigh tunneling magnetoresistance (TMR) ratio of up to approximately 107%, together with a 100% spin injection efficiency, indicating that this system possesses nearly ideal spin injection capability. This outstanding performance mainly originates from the highly selective suppression of the transmission probabilities for different spin channels by the onedimensional barrier layer, as well as the pronounced difference in transport channels between the parallel and antiparallel magnetic configurations. Furthermore, the influence of local spin manipulation on the transport properties of the device is investigated. It is found that precise control of local spin-polarization reversal at specific atomic sites, such as the AC6 site, can effectively reconstruct the local electronic-state distribution and thereby significantly modulate the spin transport behavior of the device. Remarkably, under such local regulation, the device can still maintain a TMR ratio exceeding 103% over a wide bias range, demonstrating that this system not only exhibits an excellent magnetoresistive response but also possesses strong bias stability and functional robustness.
These results indicate that one-dimensional MoI₃ atomic chains can serve not only as highly efficient tunnel barrier materials in MTJs structures, but also as a versatile platform for flexibly tuning transport performance through local spin engineering. Such features highlight their considerable potential for applications in high-performance nonvolatile spin memory, nanoscale spin logic devices, and low-dimensional quantum spintronics. This work provides a new materials perspective and physical picture for the design of high-performance MTJs based on low-dimensional magnetic systems, and lays a theoretical foundation for the development of nextgeneration spintronic devices that simultaneously feature high TMR ratios, high spin injection efficiency, and excellent tunability.