S. F. Matar, M. A. Subramanian and J. Etourneau
The electronic and magnetic structures of the ferromagnetic pyrochlore compound Tl2Mn2O7 , exhibiting colossal magnetoresistance (CMR), are self-consistently calculated within the local spin density functional theory using the augmented spherical wave (ASW) method. The influence of mixing between the different l-valence states on the chemical bonding is discussed from the site projected densities of states (DOS) and from the crystal orbital overlap population (COOP). From this a description of the nature of chemical bonding is proposed in relation with the development of the magnetic moment of Mn (2.77 µB) which is found in good agreement with experimental results. Besides, from the calculations a new magnetic property of a weakly half-metallic ferromagnet is proposed.