Crystal Growth and Intergrowth Structure of the New Heavy Fermion Materials CelrIn_5 and CeRhIn_5

摘要

The structures of the new heavy fermion materials CeIrIns and CeRhIDs have been determined by single-crystal neutron (R(F) = 0.051) and X-ray (R(F) = 0.056) diffraction, respective- ly. Both compounds adopt tetragonal strI,Jcture, space group P41mmm (No.123),Z= 1,a =b = 4.674(1) A, andc=7.501(5) A for CeIrIDs, and a = b = 4.656(2) A, and c = 7.542(1) A for CeR- hIRs. The possible presence of antisite disorder, a long-standing question on this type of structure, was excluded by both electron and neutron or X-ray diffraction. The compounds are built by monolayers of face-sharing distorted cuboctahedra [CeIn3] and monolayers of edge-sharing rectangular parallelepipeds [RhIn2] or (IrIn2], stacked alternatively in the [001] direction. There- fore, they are new members of the inhomogeneous linear homo- logous series MmT nT;m+2n. Because of their ordered intergrowth structure, the physical properties of the quasi-two-dimensional heavy electron systems CeIrIns and CeRhIns can be directly compared with the corresponding ones of their parent compound, the three-dimensional heavy fermion material CeIn3.