Light, Spin, and Symmetry at Two-Dimensional Interfaces

When two atomically thin materials are brought into contact, their interface can give rise to electronic and optical phenomena that are absent in either material alone. Particularly intriguing are heterostructures combining magnetic and nonmagnetic semiconductors, where interfacial coupling and broken symmetries can influence optical selection rules and spin-dependent electronic processes.

In this seminar, I will discuss how temperature- and polarization-resolved photocurrent spectroscopy can reveal the underlying physics of such interfaces. Focusing on a heterojunction formed between the nonmagnetic semiconductor WSe₂ and the antiferromagnetic semiconductor NiPS₃, we identify distinct photocurrent contributions associated with optical transitions in both materials, including the absorption edge and d–d excitations of NiPS₃. Circularly polarized excitation reveals additional spectral features with pronounced helicity dependence.

Surprisingly, several of these features persist across the antiferromagnetic phase transition, suggesting that their origin cannot be explained by bulk magnetic order alone. First-principles calculations provide insight into the underlying mechanisms, highlighting the roles of electric-field-induced electronic hybridization, local symmetry breaking, and spin–layer locking.

These findings demonstrate how photocurrent spectroscopy can probe the interplay between optical excitation, electronic structure, and spin-dependent carrier generation, offering a broader perspective on the emergent physics of two-dimensional interfaces.

Biography

Doron Naveh is a Full Professor in the Faculty of Engineering at Bar-Ilan University. He received his BSc in Physics and Materials Engineering and his MSc in Physics from Ben-Gurion University in 2001 and 2003, respectively, and his PhD from the Weizmann Institute of Science in 2008, where he specialized in computational materials science. He subsequently held a theoretical postdoctoral fellowship at Princeton University (2008–2009), followed by an experimental postdoctoral fellowship in Electrical and Computer Engineering at Carnegie Mellon University (2009–2012).

In 2012, Prof. Naveh joined the Faculty of Engineering at Bar-Ilan University. He was among the founding members of the Nanoelectronics Track and currently serves as the founding head of the Materials Engineering Program. His research spans advanced electronic and optoelectronic materials and devices, with particular emphasis on two-dimensional materials, van der Waals heterostructures, quantum and spin-dependent phenomena, photodetectors, and nanoscale device physics.