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Article Dans Une Revue Physical Review B Année : 2018

Higgs-mode radiance and charge-density-wave order in 2H−NbSe2

Résumé

Despite being usually considered two competing phenomena, charge-density wave and superconductivity coexist in few systems, the most emblematic one being the transition-metal dichalcogenide $H$ − NbSe$_2$ . This unusual condition is responsible for specific Raman signatures across the two phase transitions in this compound. While the appearance of a soft phonon mode is a well-established fingerprint of the charge-density-wave order, the nature of the sharp subgap mode emerging below the superconducting temperature is still under debate. In this work we use external pressure as a knob to unveil the delicate interplay between the two orders, and consequently the nature of the superconducting mode. Thanks to an advanced extreme-conditions Raman technique, we are able to follow the pressure evolution and the simultaneous collapse of the two intertwined charge-density-wave and superconducting modes. The comparison with microscopic calculations in a model system supports the Higgs-type nature of the superconducting mode and suggests that charge-density wave and superconductivity in $H$ − NbSe$_2$ involve mutual electronic degrees of freedom. These findings fill the knowledge gap on the electronic mechanisms at play in transition-metal dichalcogenides, a crucial step to fully exploit their properties in few-layer systems optimized for device applications.

Dates et versions

hal-01756873 , version 1 (03-04-2018)

Identifiants

Citer

Romain Grasset, Tommaso Cea, Yann Gallais, Maximilien Cazayous, Alain Sacuto, et al.. Higgs-mode radiance and charge-density-wave order in 2H−NbSe2. Physical Review B, 2018, 97 (9), pp.094502. ⟨10.1103/PhysRevB.97.094502⟩. ⟨hal-01756873⟩
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