The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron-phonon interaction, while the others showed evidence for electron-electron or electron-magnon interactions. Here we propose to resolve this problem by generalizing the Bloch-Grüneisen equation and using it for the analysis of the temperature dependent resistivity in TBG. It is a well-established theoretical result that the Bloch-Grüneisen equation power-law exponent, p, exhibits exact integer values for certain mechanisms. For instance, = 5 implies the electron-phonon interaction, = 3 is associated with the electron-magnon interaction and = 2 applies to the electron-electron interaction. Here we interpret the linear temperature-dependent resistance, widely observed in TBG, as p→1, which implies the quasielastic charge interaction with acoustic phonons. Thus, we fitted TBG resistance curves to the Bloch-Grüneisen equation, where we propose that is a free-fitting parameter. We found that TBGs have a smoothly varied -value (ranging from 1.4 to 4.4) depending on the Moiré superlattice constant, , or the charge carrier concentration, . This implies that different mechanisms of the charge carrier interaction in TBG superlattices smoothly transition from one mechanism to another depending on, at least, and . The proposed generalized Bloch-Grüneisen equation is applicable to a wide range of disciplines, including superconductivity and geology.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8156452 | PMC |
http://dx.doi.org/10.3390/nano11051306 | DOI Listing |
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