NEW DIAMOND-ANVIL CELL DESIGN FOR FAR-INFRARED MAGNETOSPECTROSCOPY FEATURING IN-SITU CRYOGENIC PRESSURE TUNING

A novel diamond-anvil cell (DAC) adaptation for far infrared (FIR) cry ogenic magnetospectroscopy in a small-bore magnet is reported. A desig n featuring a multibellows ram is employed to generate amplified force for in situ pressure tuning of the DAC at cryogenic temperatures with out increasing the overall diameter of the apparatus. A constructed ve rsion, using a 26-mm-diam double-bellows ram, is capable of producing 5 kN force (scalable to 10 kN with four bellows) when driven by He-4 a t 4.2 K. Signals are enhanced using paraboloidal cones to focus the FI R radiation on the sample and collect the transmitted signal. It is fe asible to record transmission spectra to energies as low as 80 cm(-1) with this apparatus using appropriate gasket-hole sizes and detectors. The pressure, magnetic field, and temperature can be tuned independen tly in the ranges 0-20 GPa (in steps as small as 0.05 GPa), 0-15 T, an d 2-300 K. We present high pressure (4.2 K) Fourier-transform FIR spec tra at fixed magnetic fields, and laser (118.8 mu m) magnetospectrosco py data on the 1s-2p(+) transition of Si donors in GaAs measured with this apparatus. (C) 1996 American Institute of Physics.