Optimized couplers for interfacial thermal transport

To find optimized interfacial thermal couplers we study thermal transport though a one dimensional atomic chain which includes three parts-two semi-infinite leads and a center region acting as a thermal coupler. It is found that the spring constant and atomic mass of an interfacial coupler can be selected to maximize interfacial thermal conductance. For the case of two lead materials with equal cutoff phonon frequencies, the interfacial system will reach a maximum thermal conductance if the coupler has the same cutoff frequency as those of the leads and its spring constant is equal to the geometric mean of those of leads. If two leads have equal acoustic impedances, one can find optimized interfacial coupler around the point where its acoustic impedance is the same as those of the leads and its spring constant is equal to the harmonic mean of those of leads. For general lead materials the interfacial thermal conductance can be optimized near the cross point of the geometric mean of impedances and harmonic mean of cutoff frequencies of the leads. Our findings can have potential applications in high performance interfacial thermal transport.