Dmk 22buc03

Single-crystals of Dy_0.7Tb_0.3FeO₃ were grown by the floating-zone method under O₂ atmosphere. Using back-reflection X-ray Laue diffractometry, thin c-oriented plates of 2.5 × 2.5 mm² were cut, lapped, and polished with a silica slurry down to ~60–80 μm with optically flat surfaces on both sides. Temperature and magnetic field treatment was done in a liquid-helium-cooled magnetic-field cryostat (Oxford Spectromag 4000-10T). For Faraday imaging, a light-emitting diode with a central wavelength of 660 nm (Thorlabs M660L4) was used along with a monochromatic digital camera (The Imaging Source DMK 22BUC03) for image acquisition. Image processing is limited to adjustments of brightness, contrast and levels and homogeneously applied to the entire image, unless noted. The images of each figure were adjusted equally. For electric field measurements, 3-nm platinum electrodes were deposited on both surfaces of the specimen.

Photoresponses of larvae of different ages were assayed in a vertical Plexiglas column (31 mm x 10 mm x 160 mm water height). The column was illuminated from above with light from a monochromator (Polychrome II, Till Photonics). The monochromator was controlled by AxioVision 4.8.2.0 (Carl Zeiss MicroImaging GmbH) via analog voltage or by a custom written Java program via the serial port. The light passed a collimator lens (LAG-65.0–53.0 C with MgF2 Coating, CVI Melles Griot). The column was illuminated from both sides with light-emitting diodes (LEDs). The LEDs on each side were grouped into two strips. One strip contained UV (395 nm) LEDs (SMB1W-395, Roithner Lasertechnik) and the other infrared (810 nm) LEDs (SMB1W-810NR-I, Roithner Lasertechnik). The UV LEDs were run at 4 V to stimulate the larvae in the column from the side. The infrared LEDs were run at 8 V (overvoltage) to illuminate the larvae for the camera (DMK 22BUC03, The Imaging Source), which recorded videos at 15 frames per second and was controlled by IC Capture (The Imaging Source).