Rectification of low-frequency thermal waves in graded SicGe1 − c

• Dispersion relation for low-frequency thermal waves in graded systems is obtained.
• Phase speed and attenuation depend on the relative direction with respect to composition gradient.
• Thin layers of graded Si/Ge may act as rectifiers of the thermal waves.
• Rectification may be switched on and off by means of a temperature gradient.

We study propagation of low-frequency thermal waves in graded SicGe1−cSicGe1−c. We show that in some ranges of stoichiometry variation one obtains rectification of thermal waves, i.e., the system allows the propagation of waves in one direction but not in the opposite one through the graded system, or through a thin graded layer separating two different systems. The rectification of low-frequency thermal waves could be switched by imposing on the graded layer a suitable temperature gradient.