Magnetic properties and phase transitions of the metallic CuX₂dichalcogenides (X=S, Se, Te) with pyrite structure

The structural and electrical properties of liquid copper selenide

“…11 we compare structural data for solid and liquid CuSe and from this comparison it can be concluded that complex anions, either of the form (Se), or (Se)f -, probably exist in the liquid state. The coexistence of complex anions and metallic conductivity has been postulated for other liquids, most notably liquid KPb (van der Lugt andGeertsma 1987, Saboungi, Blomquist, Volin andPrice 1987) where the anionic species is believed to be (Pb):-; we consider that these present experiments provide evidence that metallic conductivity and stable ionic clusters can exist together at elevated temperatures in the liquid state. It is also interesting to note that short CuCu distances appear in the liquid which are absent in the solid; these arise, presumably, in order that the negative charge on the Se pairs can be effectively screened by the copper cations.…”

“…Superconductivity has been observed in CuS, CuS,, CuSe, and CuTe, but not in CuSe or CuTe. In most cases the materials are diamagnetic, and although weak ferromagnetism has been reported in a few cases (Krill, Panissod, Lapierre, Gautier, Robert and Nassr-Eddine 1976), this may be associated with impurities (Folmer 1981).…”

DFT calculations on the electronic structure of CuTe2 and Cu7Te4

“…Searching for the electronic ground states for both compounds paramagnetic configurations were found to be the lowest in energy. That agrees with the experimental results [10]. The corresponding band structures are given in Figs.…”

“…The experimental observation of metallic conductivity shows the necessity to use an enhanced description of the electronic structure of CuTe 2 . There are earlier measurements on the magnetic susceptibility, NMR and electrical resistivity of copper dichalcogenides [10]. However, the electronic structure could not be understood and the nature of valence and conduction bands are "not really known" giving three "possible schemes" for the contribution of e g , s and/or t 2g electrons to the local susceptibilities on the Cu sites.…”

Relating Electron Configuration, Crystal Structure and Band Structure

“…peak observed in X for CoSez may be due to weak CDW behaviour. This it seems arises too in CuSz and CuSez 230 An antiferromagnetic SDW probably is responsible for the transitions observed in layered t~gCrSez231 following up on the ferromagnetism CrOz. The moment is lost in wider band divalent t~gTiS and also VS, where CDW activity was earlier suggested 13Z ,37.…”