Comparison of the temperature- and pressure-dependent behavior of the crystal structure of CrAs

The crystal structure of CrAs was investigated using synchrotron X-ray single-
crystal diffraction for separate dependences on temperature (30–400 K) and on
pressure (0–9.46 GPa). The isosymmetrical magnetostructural phase transition
at TN = 267 K can induce a change in the microstructure by twinning due to a
crossing of the orthohexagonal setting of the unit-cell parameter ratio c/b.
Within the crystal structure, one particular Cr–Cr distance exhibits anomalous
behavior in that it is nearly unaffected by temperature and pressure in the
paramagnetic phase, which is stable above 267 K and at high pressures. The
distinction of this shortest Cr–Cr distance might be of importance for the
superconducting properties of CrAs.