Pressure induced superconductivity in pristine 1T-TiSe2
The charge density wave (CDW) in 1T-TiSe2 layered compound is a rather special electronic state. Recent investigations claim that this may be a long-sought example of the "excitonic insulator", comprising a condensate of indirect excitons. In the present paper the pressure is used to first weaken and then completely suppress the CDW phase in pristine 1T-TiSe2. The superconductivity is found around the critical pressure. The new T-P phase diagram of 1T-TiSe2 reveals the superconducting dome that surrounds the CDW quantum critical point (QCP). This finding complements a recent discovery of superconductivity through copper intercalation, where another superconducting dome appears. It turns, however, that the normal states and the superconducting properties of the systems obtained by pressure
and intercalation are qualitatively different. 1T-TiSe2 thus represents a unique example where two different superconducting domes are obtained by two different methods from the same parent compound. The occurrence of the superconducting dome in the vicinity of another electronic order has attracted much attention in recent years in cuprate high temperature superconductors, heavy fermion compounds and layered organics. In these compounds, however, the superconducting dome appears on the top of magnetic QCP, which is not the case with 1T-TiSe2.
The present knowledge of the phase diagram of 1T-TiSe2. The empty space between two superconducting domes on vertical planes suggests future investigations in this compound.
Links:
Article A. F. Kusmartseva, B. Sipos, H. Berger, L. Forro, and E. Tutiš, Pressure Induced Superconductivity in Pristine 1T-TiSe2, Phys. Rev. Lett. 103 (2009)
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