Spherical Polarization Analysis for Measuring Spin Hall Materials

Strongly spin-orbit coupled materials like Topological Insulators (TI) represent a groundbreaking category of electronic materials where the interplay between charge order and spin-orbit coupling (SOC) results in an insulating bulk (with the bandgap inverted by SOC) and conductive topological surface states. In this investigation, we examine the influence of a polarized neutron beam on the surface and bulk strong SOC in Bismuth Selenide (Bi2Se3) and Platinum single crystals, respectively. Through these experiments, we demonstrate the existence of a coupling mechanism between SOC and neutron beam polarization by analyzing strong SOC materials in comparison to non-SOC materials such as Highly Oriented Pyrolytic Graphite (HOPG). We establish the sensitivity of the induced Hall voltages in Bi2Se3 and Platinum to the polarization of the incident neutron beam, contrasted with the lack of this effect in non-SOC materials. This finding opens new avenues for utilizing neutrons as a powerful tool for investigating Strong SOC materials.