Abstract
Nature Nanotechnology 2021, 16, 764-768
Observation of Superdiffusive Phonon Transport in Aligned Atomic Chains
Yang L, Tao Y, Zhu Y, Akter M, Wang K, Pan Z, Zhao Y, Zhang Q, Xu Y-Q, Chen R, Xu TT, Chen Y, Mao Z, Li D
Fascinating phenomena can occur as charge and/or energy carriers are confined in one dimension1,2,3,4. One such example is the divergent thermal conductivity (?) of one-dimensional lattices, even in the presence of anharmonic interatomic interactions鈥攁 direct consequence of the Fermi鈥揚asta鈥揢lam鈥揟singou paradox proposed in 19555. This length dependence of ?, also known as superdiffusive phonon transport, presents a classical anomaly of continued interest6,7,8,9. So far the concept has remained purely theoretical, because isolated single atomic chains of sufficient length have been experimentally unattainable. Here we report on the observation of a length-dependent ?聽extending over 42.5?碌m at room temperature for ultrathin van der Waals crystal NbSe3聽nanowires. We found that ?聽follows a 1/3 power law with wire length, which provides experimental evidence pointing towards superdiffusive phonon transport. Contrary to the classical size effect due to phonon-boundary scattering, the observed ?聽shows a 25-fold enhancement as the characteristic size of the nanowires decreases from 26 to 6.8?nm while displaying a normal鈥搒uperdiffusive transition. Our analysis indicates that these intriguing observations stem from the transport of one-dimensional phonons excited as a result of elastic stiffening with a fivefold enhancement of Young鈥檚 modulus. The persistent divergent trend of the observed thermal conductivity with sample length reveals a real possibility of creating novel van der Waals crystal-based thermal superconductors with ?聽values higher than those of any known materials.