Experimental Techniques
Sub-Kelivn cryostats
Extremely low temperatures are reached using dilution refrigerators which work akin to a conventional, continuously-cooling refrigerator except based on the circulation of isotopes of helium rather than Freon and quantum rather than classical thermodynamics. Our laboratory currently boasts three dilution refrigerators with cooling powers of 75, 200, and 400 microwatts, each outfitted with 8/10 Tesla superconducting magnets, as well as two helium-3 cryostats, one outfitted with a 14/16 Tesla magnet. We also have a pair of helium-4 cryostats capable of controlling temperature between 1.7 and 400 K, one which is cryogen-free and equipped with a 9 T magnet, and the other designed for optical measurements.
We perform electrical, magnetic, thermal, and optical measurements in these systems.
More reading: Sub-Kelvin ac magnetic susceptometry
High Pressure Techniques
Quasi-hydrostatic pressures up to 45 GPa can be reached in the laboratory using diamond anvil cells and tuned in situ via a helium membrane system. Larger samples can be measured to 2.5 GPa using BeCu clamp piston pressure cells. Further precise tuning of symmetry fields can be obtained via homebuilt uniaxial clamp cells.
We perform a wide range of measurements inside the pressure cells, including electrical transport and Hall Effect, magnetic susceptibility, structural and magnetic x-ray diffraction, pump-probe optical spectroscopy, Raman scattering, and synchrotron Mossbauer measurements,
More reading:
Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in situ tunability
A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements
Four-probe electrical measurements with a liquid pressure medium in a diamond anvil cell
High-pressure X-ray measurements
We are frequent users of the Advanced Photon source at the Argonne National Laboratory, with experiments performed at Sectors 2, 4, 6, 8, 11, 13, 16, and 33. We mainly focus on quantum critical behaviors of both correlated charge and magnetic systems, using diamond anvil cells and mainly x-ray diffraction techniques, including advancing the state of the art in magnetic x-ray diffraction at high pressures.
More reading: X-ray magnetic diffraction under high pressure