Spin polarization detection via chirality-induced tunneling currents in layered semiconductors

Two-dimensional flat-band systems offer a platform for exploring emergent phenomena and correlated electronic states. In this talk, we investigate few-layer indium selenide (InSe), a material known for its remarkable optical, electrical, and thermoelectric properties, which hosts a van Hove singularity at the valence band edge without requiring twist angle manipulation. We demonstrate how tunneling photocurrents in gated semiconductors serve as an effective probe for the flat-band energy position, supported by ambipolar transport and photoluminescence measurements. A distinct change in tunneling mechanisms emerges near the van Hove singularity, allowing for its detection up to room temperature. Moreover, we study the interaction between light chirality and electron spins in InSe under a magnetic field, revealing an asymmetric tunneling response under circularly polarized light. This enables the electrical detection of light's chirality and confirms the theoretical prediction of spin-polarized hole accumulation at the flat valence band with increasing laser power. These findings provide new insights into flat-band physics and the interplay of chirality and spin, with potential applications in future technologies.