Abstract
Recently, the prediction of structural degeneracy for the ground state of by ab initio methods has stimulated research on this system. We investigated the structural and thermodynamic properties by single crystal and powder x-ray diffraction (at zero and high pressure) as well as by neutron powder diffraction, demonstrating that the C14 Laves phase structure is stable down to a temperature of and up to applied pressure of . The bulk modulus and enthalpy of formation (measured by high-temperature drop calorimetric experiments) of are found to be and , respectively, in nice agreement with the ab initio calculated results. The experimental bulk thermal-expansion data of resembles that of a typical metal. However, the temperature-dependent electrical resisitivity shows that there is a power law with at low temperature quite different from simple metals which originates probably from scattering of the charge carriers on the frustrated Mn moments. The phonons have been investigated in detail by comparing results of ab initio calculations with neutron spectra and experimental specific-heat data.
5 More- Received 30 May 2006
DOI:https://doi.org/10.1103/PhysRevB.74.224109
©2006 American Physical Society