PerspectivePhysics

Sounding out optical phonons

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Science  01 Sep 2017:
Vol. 357, Issue 6354, pp. 873-874
DOI: 10.1126/science.aao2446

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Summary

Technologies based on microelectronic integrated circuits are driven by electronic devices in which the electron quasiparticles in solid-state components are manipulated to process, transfer, and store information. Much of the world's energy supply is consumed by these processes, with a considerable amount ending up as heat, generated through interactions between the electrons and the lattice of ions in the solid. Although heat generated from electron-lattice interactions in electronic devices is usually considered to be an inconvenient waste product, a prominent counterexample that exploits the coupling is found in thermoelectric devices, in which a thermal gradient is used to generate a voltage (the Seebeck effect), or a flow of electric current is used for cooling (the Peltier effect). Because the quasiparticles that carry heat in crystals are the quantized lattice vibrations called phonons, thermoelectric generators and refrigerators are examples of products based on electron-phononic devices. We examine the exciting steps that are being made in the manipulation and application of phonons, toward phonon-only–based phenomena and devices. Recent developments in the emerging field of “phononics” are providing a promising route to the development of phononic devices as a complement to electronics in future technologies (see the figure).