Acoustic phonon transport through a T-shaped quantum waveguide

We study the transmission coefficient and thermal conductivity for acoustic phonons crossing a T-shaped quantum waveguide at low enough temperatures by use of the scattering-matrix method. Our results show that relatively small changes in the stub length and width can induce strong variations in the phonon transmission and thermal conductivity. Compared with the electron case in such a structure, acoustic phonon transmission and thermal conductivity exhibit some novel and interesting features. The phonon transmission coefficients and thermal conductivity can be artificially controlled by adjusting the parameters of the proposed microstructure.