Fully spin-polarized current and pure spin current induced by photogalvanic effect in the 2D half-metal YSi2N4

Compared with traditional electronic devices, spintronic devices offer the benefits of lower power consumption, faster transmission speeds, and higher integration densities. Therefore, seeking a direct and efficient method to flexibly generate spin currents in a single device, especially fully spin-polarized current (FSPC) and pure spin current (PSC), remains crucial. Inspired by this, we design a spin optoelectronic device based on the half-metal YSi2N4, and investigate its transport behavior influenced by photogalvanic effects. Remarkably, the YSi2N4 spin device can generate FSPC and PSC under linearly polarized light irradiation with parallel electrode magnetic configuration (PC) or anti-parallel configuration (APC). For the YSi2N4 device in PC, FSPC can be generated at any polarization angle when the photon energy is less than 2.36 eV, fulfilling the spin filtering effect. For the device in APC, PSC can be obtained across an extensive range of photon energy, which acts as an important carrier for spin transport. More interestingly, the magnetoresistance ratio of the YSi2N4 device generally exceeds 90%, demonstrating excellent spin-valve effect. Our work suggests that the monolayer YSi2N4 spin optoelectronic device can generate FSPC and PSC flexibly and efficiently, making it an advanced candidate for multifunctional spin devices.