Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Nat Commun. 2023 Feb 17;14(1):916. doi: 10.1038/s41467-023-36420-4.
Integrated phononics plays an important role in both fundamental physics and technology. Despite great efforts, it remains a challenge to break time-reversal symmetry to achieve topological phases and non-reciprocal devices. Piezomagnetic materials offer an intriguing opportunity as they break time-reversal symmetry intrinsically, without the need for an external magnetic field or an active driving field. Moreover, they are antiferromagnetic, and possibly compatible with superconducting components. Here, we develop a theoretical framework that combines linear elasticity with Maxwell's equations via piezoelectricity and/or piezomagnetism beyond the commonly adopted quasi-static approximation. Our theory predicts and numerically demonstrates phononic Chern insulators based on piezomagnetism. We further show that the topological phase and chiral edge states in this system can be controlled by the charge doping. Our results exploit a general duality relation between piezoelectric and piezomagnetic systems, which can potentially be generalized to other composite metamaterial systems.
声子集成在基础物理和技术中都起着重要作用。尽管已经付出了巨大的努力，但要打破时间反转对称性以实现拓扑相和非互易器件仍然是一个挑战。压磁材料提供了一个有趣的机会，因为它们无需外部磁场或主动驱动场即可内在地打破时间反转对称性。此外，它们是反铁磁体，并且可能与超导组件兼容。在这里，我们通过压电性和/或压磁性（超越通常采用的准静态近似）将线性弹性与麦克斯韦方程组结合起来，开发了一个理论框架。我们的理论预测并通过数值演示了基于压磁的声子 Chern 绝缘体。我们进一步表明，该系统中的拓扑相和手性边缘态可以通过电荷掺杂来控制。我们的结果利用了压电器件和压磁器件系统之间的一般对偶关系，这可能会推广到其他复合超材料系统。
