Lattice collapse and quenching of magnetism in CaFe2As2 under pressure: A single crystal neutron and x-ray diffraction investigation

Goldman, A. I.; Kreyssig, A.; Prokes, K.; Pratt, D. K.; Argyriou, D. N.; Lynn, J. W.; Nandi, S.; Kimber, S. A. J.; Chen, Y.; Lee, Y. B.; Samolyuk, G.; Leao, J. B.; Poulton, S. J.; Bud'ko, S. L.; Ni, N.; Canfield, P. C.; Harmon, B. N.; McQueeney, R. J.

Lattice collapse and quenching of magnetism in CaFe2As2 under pressure: A single crystal neutron and x-ray diffraction investigation

Authors

Description

Single crystal neutron and high-energy x-ray diffraction have identified the phase lines corresponding to transitions between the ambient-pressure tetragonal (T), the antiferromagnetic orthorhombic (O) and the non-magnetic collapsed tetragonal (cT) phases of CaFe2As2. We find no evidence of additional structures for pressures up to 2.5 GPa (at 300 K). Both the T-cT and O-cT transitions exhibit significant hysteresis effects and we demonstrate that coexistence of the O and cT phases can occur if a non-hydrostatic component of pressure is present. Measurements of the magnetic diffraction peaks show no change in the magnetic structure or ordered moment as a function of pressure in the O phase and we find no evidence of magnetic ordering in the cT phase. Band structure calculations show that the transition results in a strong decrease of the iron 3d density of states at the Fermi energy, consistent with a loss of the magnetic moment.
List of authors in metadata and typos in labeling of inset in Fig. 1(a) corrected. One ref. added. No other changes