Detailed electrical and photoemission studies were carried out to probe the chemical nature of the insulating ground state of VO_{2}, whose properties have been an issue for accurate prediction by common theoretical probes. The effects of a systematic modulation of oxygen overstoichiometry of VO_{2}from 1.86 to 2.44 on the band structure and insulator–metal transitions are presented for the first time. Results offer a different perspective on the temperature and dopinginduced IMT process. They suggest that charge fluctuation in the metallic phase of intrinsic VO_{2}results in the formation of e^{−}and h^{+}pairs that lead to delocalized polaronic V^{3+}and V^{5+}cation states. The metaltoinsulator transition is linked to the cooperative effects of changes in the V–O bond length, localization of V^{3+}electrons at V^{5+}sites, which results in the formation of V^{4+}–V^{4+}dimers, and removal of
Surface plasmons, which allow tight confinement of light, suffer from high intrinsic electronic losses. It has been shown that stimulated emission from excited electrons can transfer energy to plasmons and compensate for the high intrinsic losses. Todate, these realizations have relied on introducing an external gain media coupled to the surface plasmon. Here, we propose that plasmons in twodimensional materials with closely located electron and hole Fermi pockets can be amplified, when an electrical current bias is applied along the displaced electronhole pockets, without the need for an external gain media. As a prototypical example, we consider WTe_{2}from the family of 1T
 Award ID(s):
 1741660
 Publication Date:
 NSFPAR ID:
 10385037
 Journal Name:
 Nature Communications
 Volume:
 13
 Issue:
 1
 ISSN:
 20411723
 Publisher:
 Nature Publishing Group
 Sponsoring Org:
 National Science Foundation
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