부산대학교 도서관

The electronic characteristics of ZrCuGe2, ZrCuSi2, and HfCuSi2 are systematically investigated using 63Cu NMR spectroscopy. The quadrupole splittings, Knight shifts, and spin-lattice relaxation times on each individual compound have been identified. We found that the observed electric field gradient is consistent with the covalent bonding nature within the Cu atomic layers. The Knight shifts together with relaxation rates provide a measure of Cu d partial Fermi-level density of states, Nd(EF). Universally small Nd(EF) was found in all studied materials, suggests that the Cu d states are well below the Fermi energy and therefore the characteristic electronic structure near EF is primarily of sp type. We further pointed out that the low Nd(EF) value is an important factor for the lack of superconductivity in these Cu-based intermetallics within the ZrCuSiAs-type structure. [ABSTRACT FROM AUTHOR]