Fig. 4: Controllable and tunable characteristics of BP under external potential field.

a Different level of magnetic susceptibility conducted by incongruous external field along perpendicular and parallel direction. b One example for demonstrating the discrepant active behavior of biosensing reaction along perpendicular and parallel direction of few-layer black phosphorus. c Schematic structures of z-PNR (left) and a-PNR (right), indicating PNRs with typical layer-edge types and electrical transport directions of zigzag and armchair, respectively. d, e Transformation behaviors of energy bandgap and effective carrier masses under applied strain (ε) in a-PNR and z-PNR, respectively. f Electron mobilities along zigzag (μ_x, black curve) and armchair (μ_y, red curve) directions in single-layer black phosphorus at room temperature under varied in-plane biaxial strain. g Same research objectives as f, under varied uniaxial strain along x-direction. h, i Electric field tuning effects of BP oscillator strength that show light polarized along armchair (AC) axis and zigzag (ZZ) axis, respectively. Images of a and b used with permission from John Wiley and Sons⁷⁹. Images of c–e adapted with permission from ref. ⁸⁰ copyright 2014, American Chemical Society. Images of f and g adapted with permission from ref. ³⁴ copyright 2014, American Chemical Society. Images of h and i adapted with permission from ref. ⁹² copyright 2019, American Chemical Society.