Violation of the Curie law in Na2V3O7 as the crystal-field and   spin-orbit coupling effect
  We have shown that the observed drastic violation of the Curie-Weiss law in Na2V3O7, reported in Phys. Rev. Lett. 90 (2003) 167202, is caused by conventional crystal-field interactions and the intra-atomic spin-orbit coupling of the V4+ ion. The fine discrete electronic structure of the 3d1 configuration, with a substantial orbital moment, is the reason for anomalous low-temperature properties of Na2V3O7. According to the Quantum Atomistic Solid-State Theory (QUASST) Na2V3O7 is expected to exhibit pronounced heavy-fermion phenomena at low temperatures. This study confirm our earlier claim that the orbital moment has to be unquenched in description of 3d-atom compounds.   PACS: 71.70.E, 75.10.D   Keywords: crystal-field interactions, spin-orbit coupling, orbital moment, Na2V3O7 
R.J. Radwanski and Z. Ropka