New diamond-anvil cell design for far infrared magnetospectroscopy featuring in situ cryogenic pressure tuning

Abstract

A novel diamond-anvil cell (DAC) adaptation for far infrared (FIR) cryogenic magnetospectroscopy in a small-bore magnet is reported. A design featuring a multibellows ram is employed to generate amplified force for in situ pressure tuning of the DAC at cryogenic temperatures without increasing the overall diameter of the apparatus. A constructed version, 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 4He at 4.2 K. Signals are enhanced using paraboloidal cones to focus the FIR radiation on the sample and collect the transmitted signal. It is feasible 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 independently in the ranges 0–20 GPa (in steps as small as 0.05 GPa), 0–15 T, and 2–300 K. We present high pressure (4.2 K) Fourier-transform FIR spectra at fixed magnetic fields, and laser (118.8 μm) magnetospectroscopy data on the 1s–2p+ transition of Si donors in GaAs measured with this apparatus.

A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements

“…(25.4 mm) for compatibility with the Physical Properties Measurement System (PPMS) line of cryostats from Quantum Design; this design rule also provides compatibility with a wide range of systems, including variable-temperature inserts designed for 32 and 50 mm magnet bores and helium-3 and dilution refrigerator systems with similar space constraints. Being intermediate in size between the two limits mentioned above, this cell is similar to a previous design, 4 but is slightly smaller in diameter and much simpler in construction. It preserves both spring washers and the helium membrane structure for continuous fine tuning of pressure without the need to thermally cycle to room temperature.…”

“…The pressurization method typically consists of Belleville disk springs, a split spring, 3,5 or a turnbuckle, 6,7 and possibly a lever arm 1 or a helium membrane/bellows actuator for in situ adjustment of the pressure. 4,8 Miniature DAC systems have been developed with crosssectional diameters under 9 mm 6,7 for magnetization measurements in the tight confines of a superconducting quantum interference device (SQUID) magnetometer. In order to fit the tight space constraints, the cell designs must simplify or eliminate many general components of a DAC system.…”

“…[1][2][3][4][5][6][7] Among all high-pressure vessels, diamond anvil cells (DAC) are most commonly used due to the combination of a large accessible pressure range and a relatively compact structure. Although early designs could be cumbersome, 1, 2 a contemporary full sized diamond anvil cell is typically 2 in.…”

High-Pressure Studies of Semiconductors in the Far-Infrared: Donor States in Quasi-2D

“…la and b [6]. The principal components of this apparatus are fabricated from stainless steel, except the DAC itself (parts 18-25) made from hardened BeCu alloy, the copper paraboloidal FIR focusing cones (15 and 26), the quartz optical fiber (12), and the Ga-doped Ge FIR detector (11).…”

“…However, without in situ tuning, it becomes largely a matter of luck to detect the many fascinating resonant and anticrossing interactions that are possible in semiconductors. This has been the motivation for the recent instrumentation advances by the SUNY at Buffalo group [6].…”