Tunneling magnetoresistance and light modulation in Fe4N(La2/3Sr1/3MnO3)/C60/Fe4N single molecule magnetic tunnel junctions

Abstract

Due to the development of devices with rapid and high-density information storage capabilities, spin-polarized transport through a single molecule has attracted much attention. Here, the spin-dependent transport properties and light modulation of Fe₄N/C₆₀/Fe₄N and La_2/3Sr_1/3MnO₃/C₆₀/Fe₄N (LSMO/C₆₀/Fe₄N) single-molecule magnetic tunnel junctions were investigated systematically by first-principles quantum transport calculations. At equilibrium, a positive tunneling magnetoresistance (TMR) is found in the Fe₄N/C₆₀/Fe₄N junction. A negative TMR appears in the LSMO/C₆₀/Fe₄N junction, which can become positive upon applying a bias voltage of 0.3 V. Moreover, the magnetization configuration and bias voltage can effectively tailor the spin injection of the Fe₄N/C₆₀/Fe₄N junction, but cannot affect the LSMO/C₆₀/Fe₄N junction with a spin injection efficiency of 100%. Additionally, the LSMO/C₆₀/Fe₄N junction with different electrodes becomes a system lacking spatial reversal symmetry, so its photoresponse is much smaller than that of the Fe₄N/C₆₀/Fe₄N junction. The fully spin-polarized photocurrent and spin battery can be obtained in both magnetic tunnel junctions by properly tailoring the photon energy and polarization angle. Interestingly, it is possible to switch the two poles of the spin battery by the magnetization configuration in the LSMO/C₆₀/Fe₄N junction. These results provide theoretical guidance for the design of light-modulated single-molecule spintronic devices.