Ishizuka Hiroaki, Fahimniya Ali, Guinea Francisco, Levitov Leonid
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo, 113-8656, Japan.
Nano Lett. 2021 Sep 22;21(18):7465-7471. doi: 10.1021/acs.nanolett.1c00565. Epub 2021 Sep 13.
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 moiré 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 () resistivity, both of which are directly tunable by the moiré twist angle.
在珀塞尔效应中，通过减小光学模式体积可提高光发射器的效率。在此，我们预测通过压缩电子万尼尔轨道可实现类似的电子 - 声子（el-ph）散射增强。重塑的万尼尔轨道是石墨烯莫尔超晶格的一个显著特征，其中轨道大小可通过扭转角进行调节。轨道尺寸的减小会导致el-ph相互作用强度增强，产生的值远大于原始单层石墨烯中的值。增强的耦合提高了el-ph散射率，使其高于平带增强电子态密度所预期的值。增强的声子发射和散射率通过诸如电子 - 晶格冷却和线性温度（）电阻率等可观测现象体现出来，这两者均可通过莫尔扭转角直接调节。
