Fig. 5: Extrinsic chirality of helically arranged MPs.
Experimental set-ups used to induce left-handed (a) or right-handed (b) helical magnetic fields. Two bar magnets (gray flat rectangular bar) were positioned orthogonally in a cross configuration, with their axes oriented at 45° (a) and 135° (b) relative to the light propagation direction (yellow arrow, y axis). c Schematic illustration of the cross-sectional planes used in the magnetic field simulations. Each color represents a specific y-position along the light propagation direction (red: –0.5 cm; orange: –0.25 cm; green: 0 cm; blue: +0.25 cm; purple: +0.5 cm). The origin (0, 0, 0) is defined as the midpoint of the line connecting the centers of the two bar magnets. Simulated magnetic field vector plots corresponding to 45° (d) and 135° (e) cross configurations of bar magnets (NdFeB magnet, 20 × 10 × 1 mm3) placed with an end-to-end separation distance of 1.5 cm. The arrows represent the magnetic field direction marked every 0.25 cm along the light propagation direction (y direction). The color of each vector corresponds to a specific y-position marked in (c). The black dot represents the central point of the simulation plane at (x, z) = (0, 0). The red and blue curved arrows indicate the rotational orientation of the magnetic field with respect to the light propagation direction. The variations in the apparent lengths of the magnetic field vectors arise from their tilt relative to the x–z plane. The scale bars represent 200 µm for both plots. f CD and g-factor spectra of MPs with AuNR aspect ratios of 2.3, 2.7, 3.0, and 3.4 under helical magnetic fields (20 mT) with 45° (red) and 135° (blue) magnet settings along with the data collected without a magnetic field (black). Source data are provided as a Source Data file.
