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

TitleLattice collapse and quenching of magnetism in CaFe2As2 under pressure: A single-crystal neutron and x-ray diffraction investigation
Publication TypeJournal Article
Year of Publication2009
AuthorsGoldman AI, Kreyssig A, Prokes K, Pratt DK, Argyriou DN, Lynn JW, Nandi S, Kimber SAJ, Chen Y, Lee YB, Samolyuk G, Leao JB, Poulton SJ, Bud'ko SL, Ni N, Canfield PC, Harmon BN, McQueeney RJ
Journal TitlePhysical Review B
Volume79
Pages024513
Date Published01/01
ISBN Number1098-0121
Accession NumberISI:000262978100090
Keywordsarsenic alloys, band structure, calcium alloys, crystal structure, electronic density of states, fermi level, iron alloys, magnetic hysteresis, magnetic moments, magnetic structure, neutron diffraction, phase diagrams, superconducting materials, x-ray dif
Abstract

Single-crystal neutron and high-energy x-ray diffraction measurements have identified the phase lines corresponding to transitions among the ambient-pressure paramagnetic tetragonal (T), the antiferromagnetic orthorhombic (O), and the nonmagnetic collapsed tetragonal (cT) phases of CaFe2As2. We find no evidence of additional structures for pressures of 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 nonhydrostatic 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 into the cT phase results in a strong decrease in the iron 3d density of states at the Fermi energy, consistent with a loss of the magnetic moment.

URL<Go to ISI>://000262978100090
DOI10.1103/Physrevb.79.024513