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Pressure induced collapse of the charge density wave and Higgs mode visibility in 2H-TaS$_2$

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 نشر من قبل Romain Grasset
 تاريخ النشر 2018
  مجال البحث فيزياء
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The pressure evolution of the Raman active electronic excitations of the transition metal dichalcogenides 2H-TaS$_2$ is followed through the pressure phase diagram embedding incommensurate charge-density-wave and superconducting states. At high pressure, the charge-density-wave is found to collapse at 8.5~GPa. In the coexisting charge-density-wave and superconducting orders, we unravel a strong in-gap superconducting mode, attributed to a Higgs mode, coexisting with the expected incoherent Cooper-pair breaking signature. The latter remains in the pure superconducting state reached above 8.5~GPa. Our report constitutes the first observation of such Raman active Higgs mode since the longstanding unique case 2H-NbSe$_2$.



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