PHONON-VALVE · Designing Novel Phonon Valve Device through Ferroic Domain Wall Engineering

Designing Novel Phonon Valve Device through Ferroic Domain Wall Engineering

In this project we address the possibility of creating a conceptually new device that aims at controlling the heat transport. The mechanism would be similar to a switch for heat propagation: enabling (state ON) or inhibiting (state OFF) the heat from flowing along a given path. We call this device a “phonon valve” as phonons, quasiparticles accounting for the mechanical vibrations in solids, are the main heat carriers in insulating crystalline solids. Thus, if phonons are blocked or scattered somehow, heat would not flow. Then, the idea is to design a “phonon barrier” that can be opened or closed at will by using an applied electric field. For a practical and realizable device, the activated and deactivated states should be reversible (you should be able to open the valve again when you have closed it and vice versa) and robust (the effect of opening and closing the valve should last). Hence, the problem is reduced to design the most appropriate material to meet the requirements of active phonon barrier. Ferroelectric materials naturally form internal and distinctive regions, called ferroelectric domains, each of them characterized by the polarization. The borders between these domains, domain walls, are intrinsic interfaces within the material. These interfaces may be effective centres of phonon scattering, so they would accomplish the first requirement for the phonon valve: the existence of a barrier of phonons. Second requirement is the possibility of opening and closing the phonon valve, which is also expected to be met in these materials: an electric field is able to erase and create domain walls. Third requirement is to be reversible and robust. This criterion is also expected to be fulfilled as the domain walls are stable once the electric field is removed and the process of creation/destruction of domain walls is reversible for a large number of cycles. Because of all these reasons ferroelectrics are excellent candidates for this job. Regarding the benefits for society it is worth observing that many of the major technological breakthroughs occurring in the last few decades rely on our great capability to manipulate two elementary particles: electrons and photons. Both of them are the basis of present-day electronics, photonics and semiconductor industry in general, including all electronic media (TV, computers, smartphones, etc), wire and wireless communications, energy harvesting, magnetic data storage, etc. If we manage to achieve a similar degree of control over phonons, we could start developing a completely new technology: the so-called “phononics”. This new technology may open a new way of communication or create new data storage devices and computers based on phonons. Additionally, as manipulating phonons entails manipulating the heat flow it could lead to control the thermal energy at will, propelling new possibilities for energy management, including storage and harvesting.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз