Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

The electromagnetic and thermal properties of a heavy fermion CeNi₂Ge₂ are investigated using first-principle methods with local density approximation (LDA) and fully relativistic approaches. The Ce f-bands are located near the Fermi energy E_F and hybridized with the Ni-3d states. This hybridization plays important roles in the characteristics of this material. The fully relativistic approach shows that the 4f states split into 4f_7/2 and 4f_5/2 states due to spin-orbit coupling effects. It can be found that within the LDA calculation, the density of states near the Fermi level are mainly of Ce-derived 4f states. The Ni-derived 3d states have high peaks around -1.7eV and spreaded over wide range around the Fermi level. The calculated magnetic of CeNi₂Ge₂ with LDA method does not match with that of experimental result because of strong correlation interaction between electrons in f orbitals. The calculations show that the specific heat coefficient underestimates the experimental value by a factor of 19.1. The discrepancy between the band calculation and experiment for specific heat coefficient is attributed to the formation of a quasiparticle. Because of the volume contraction, the exchange interaction between the f states and the conduction electrons is large in CeNi₂Ge₂, which increases the quasiparticle mass. This will result in the enhancement of the specific hear coefficient.