Observation of superconducting collective modes from competing pairing instabilities in single-layer NbSe2
In certain unconventional superconductors with sizable electronic correla-tions, the availability of closely competing pairing channels leads to char-acteristic soft collective fluctuations of the order parameters, which leavefingerprints in many observables and allow the phase competition to bescru...
| Autores: | , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | Universidad Autónoma de Madrid |
| Repositorio: | Biblos-e Archivo. Repositorio Institucional de la UAM |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.uam.es:10486/713968 |
| Acceso en línea: | http://hdl.handle.net/10486/713968 https://dx.doi.org/10.1002/adma.202206078 |
| Access Level: | acceso abierto |
| Palabra clave: | 2D materials Collective modes Electronic structure Molecular beam epitaxy Superconductivity Transition metal dichalcogenides Física |
| Sumario: | In certain unconventional superconductors with sizable electronic correla-tions, the availability of closely competing pairing channels leads to char-acteristic soft collective fluctuations of the order parameters, which leavefingerprints in many observables and allow the phase competition to bescrutinized. Superconducting layered materials, where electron–electroninteractions are enhanced with decreasing thickness, are promising can-didates to display these correlation effects. In this work, the existence ofa soft collective mode in single-layer NbSe 2 , observed as a characteristicresonance excitation in high-resolution tunneling spectra is reported. Thisresonance is observed along with higher harmonics, its frequency Ω/2Δ isanticorrelated with the local superconducting gap Δ, and its amplitudegradually vanishes by increasing the temperature and upon applying amagnetic field up to the critical values (TC and HC2 ), which sets an unambig-uous link to the superconducting state. Aided by a microscopic model thatcaptures the main experimental observations, this resonance is interpretedas a collective Leggett mode that represents the fluctuation toward a proxi-mate f-wave triplet state, due to subleading attraction in the triplet channel.These findings demonstrate the fundamental role of correlations in super-conducting 2D transition metal dichalcogenides, opening a path towardunconventional superconductivity in simple, scalable, and transferable 2D superconductors |
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