Nuclear resonant inelastic X-ray scattering at high pressure and low temperature

Abstract

A new synchrotron radiation experimental capability of coupling nuclear resonant inelastic X-ray scattering with the cryogenically cooled high-pressure diamond anvil cell technique is presented. The new technique permits measurements of phonon density of states at low temperature and high pressure simultaneously, and can be applied to studies of phonon contribution to pressure-and temperature-induced magnetic, superconducting and metalinsulator transitions in resonant isotope-bearing materials. In this report, a pnictide sample, EuFe 2 As 2 , is used as an example to demonstrate this new capability at beamline 3-ID of the Advanced Photon Source, Argonne National Laboratory. A detailed description of the technical development is given. The Fe-specific phonon density of states and magnetism from the Fe sublattice in Eu 57 Fe 2 As 2 at high pressure and low temperature were derived by using this new capability.

A compact membrane-driven diamond anvil cell and cryostat system for nuclear resonant scattering at high pressure and low temperature

“…The PDOS was extracted from the data using the PHOENIX package 28 . The Fe PDOS is in good agreement with the previous results [19,27]. The derived Lamb-Mössbauer factor are 0.891(3) and 0.887 (2).…”

“…1. The current mini-pDAC is an improved version of the earlier design 19 with its body length extended by about 6 mm to improve its stability. The standard mini-pDAC is made of hardened Vascomax 350 with a hardness of Rockwell C55.…”

“…For high pressure experiments dealing with small sizes (~ 10 microns) of samples, a continuous-liquid-helium-flow cryostat is generally chosen to avoid possible vibration of the sample. In our previous design 19 , a commercial cryostat was used. Since the DAC holder was not directly cooled by the liquid helium, the lowest sample temperature of the system was limited to 24 K. In our new design of the flow cryostat, the liquid helium flows through the copper holder of the mini-pDAC as shown in Fig.…”

“…NRIXS experiments under extreme conditions of pressure 13 and temperature 14 have been performed extensively, and studies under high pressure and high temperature have been carried out using the laser heated diamond anvil cells techniques [15][16][17][18] . Recently we added new capabilities at 3-ID, Advanced Photon Source (APS), Argonne National Laboratory (ANL), that made it possible to perform simultaneous SMS and NRIXS experiments at high pressure (HP) and low temperature (LT) 19 . However, in our earlier development, the lowest temperature reached on the sample was around 20K due to the fact that the DAC holder is not directly cooled by the liquid He.…”

Microscopic phase diagram of LaFeAsO single crystals under pressure

“…SMS spectra were recorded between 13 and 125 K and at applied pressures between 0.5 and 7.5 GPa using a special He-flow cryostat and a miniature diamond anvil cell . 11,12 Diamond anvils with 800 µm culet size were used. A Re gasket was preindented to 140 µm and a hole of 400 µm diameter was EDM drilled to act as a sample chamber.…”