Pressure Cells

A high pressure facility is available for all magnets at the Magnet Lab to perform both electrical transport and optical measurements over a wide range of sample volumes and attainable pressures under conditions of both hydrostatic and uniaxial stress. Diamond anvil cells are available for optical and transport measurements in both pulsed and DC fields. Conventional miniature piston-cylinder cells that can reach 1.7 GPa and have provisions for fiber optic access and electrical leads are available, but the main thrust in high pressure techniques is focused on diamond-anvil cell [DAC] technology. Although the available sample space in a DAC is small (typically a 300-700 um diameter cylinder, 60-120 um thick), two to six electrical leads can be attached to single crystal platelets only 100 um on an edge and as thick as 40 um. Spectroscopic measurements are limited only by the 10 kN load that the DAC can sustain and the optical window material, diamond. Type II diamond anvils will be available for infrared studies. UV studies can be carried out in a sapphire-ball cell designed by Professor Daniels from the University of Delaware.

To address the experimental restrictions of sample orientation and cryogenic temperatures in DC and pulsed magnetic fields, four different DACs have been designed (see table below). All are made entirely of BeCu and have optical ports and provisions for either miniature triaxial cable or shielded twisted pairs. The largest of the three DACs provides the highest pressures. DAC #2 was designed with its small diameter and thin wall to minimize eddy current heating of the sample prior to data acquisition in pulsed magnets. This particular cell is small enough to freely rotate within a 12 mm sphere and thus enables orientation-dependent work to millikelvin temperatures and pulsed fields to 50 T and higher. Both cells #1 and #2 support a minimal load of 10 kN. DAC #3 and DAC #4 are intended for microkelvin work and possibly heat capacity studies.

Users planning high pressure experiments should answer some questions about their sample(s).