期刊
NANO LETTERS
卷 21, 期 18, 页码 7465-7471出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.1c00565
关键词
twisted bilayer graphene; Purcell effect; linear-T resistivity; electron-lattice cooling; electron-phonon coupling; moire structure
类别
资金
- JSPS KAKENHI [JP18H03676, JP18H04222, JP19K14649]
- UTokyo Global Activity Support Program for Young Researchers
- Science and Technology Center for Integrated Quantum Materials, NSF [DMR-1231319]
- Army Research Office [W911NF-18-1-0116]
- European Commission, under the Graphene Flagship, Core 3 [881603]
- grant NMAT2D (Comunidad de Madrid, Spain)
- grant SprQuMat
- Ministerio de Ciencia e Innovacion, Spain [SEV-2016-0686]
The study discusses the control of electron-phonon scattering strength by altering the size of electronic Wannier orbitals to achieve an enhancement effect similar to the Purcell effect, and the specific manifestations of this phenomenon in graphene moire superlattices.
In the Purcell effect, the efficiency of optical emitters is enhanced by reducing the optical mode volume. Here we predict an analogous enhancement for electron-phonon (el-ph) scattering, achieved by compressing the electronic Wannier orbitals. Reshaped Wannier orbitals are a prominent attribute of graphene moire superlattices, where the orbital size is tunable by the twist angle. A reduction in the orbital size leads to an enhancement in the el-ph interaction strength, yielding the values considerably larger than those in pristine monolayer graphene. The enhanced coupling boosts the el-ph scattering rates, pushing them above the values expected for the flat-band-enhanced density of electronic states. The enhanced phonon emission and scattering rates are manifested through the observables such as the electron-lattice cooling and the linear-temperature (T) resistivity, both of which are directly tunable by the moire twist angle.
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