Yusuf Wicaksono is a postdoctoral research fellow in the Quantum Materials Design Group at MANA, NIMS. He received his Ph.D. in Materials Engineering Science from Osaka University. His research combines first-principles electronic-structure calculations, Wannier tight-binding models, and response theory to study spin-orbit coupling, quantum geometry, optoelectronic and spintronic phenomena in two-dimensional materials and interfaces.

Noncentrosymmetric monolayer transition-metal dichalcogenides support a bulk photovoltaic shift current, but high crystal symmetry constrains the third-rank photoconductivity tensor and can cancel the dc response to unpolarized light. Here we use layer-selective magnetic proximity to lift this pristine D₃h constraint in monolayer MoS₂. From fully relativistic density-functional theory, we construct a 22-orbital Wannier Hamiltonian that reproduces the bands around the gap. Proximity is modeled by an exchange term on the lower S sublayer, so the exchange direction controls the point symmetry. We calculate the independent-particle shift conductivity with a gauge-covariant Wannier formulation, resolving transitions between the two highest valence and two lowest conduction bands [1–3].

For pristine MoS₂, symmetry-related tensor components cancel in the unpolarized-light average, and out-of-plane exchange retains C₃ and the cancellation. In-plane exchange lowers the symmetry to Cₛ (C₁ for generic canting), making tensor components inequivalent and producing finite armchair and zigzag currents. At Δ = 0.01 eV, pronounced features appear around 1.7–2.1 eV; rotating or canting the magnetization changes their sign and magnitude. Layer-selective exchange therefore offers nonvolatile control of polarization-insensitive photodetectors and reconfigurable nonlinear optoelectronics in two-dimensional semiconductors.

1. J. E. Sipe and A. I. Shkrebtii, Phys. Rev. B 61, 5337 (2000). DOI: 10.1103/PhysRevB.61.5337
2. S. M. Young and A. M. Rappe, Phys. Rev. Lett. 109, 116601 (2012). DOI: 10.1103/PhysRevLett.109.116601
3. J. Ibañez-Azpiroz, S. S. Tsirkin, and I. Souza, Phys. Rev. B 97, 245143 (2018). DOI: 10.1103/PhysRevB.97.245143