Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary.
National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia.
Phys Rev Lett. 2015 Sep 18;115(12):127203. doi: 10.1103/PhysRevLett.115.127203. Epub 2015 Sep 15.
Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO_{3} over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.
多铁性材料允许磁控电极化和电控磁化。这些静态磁电（ME）效应非常有趣：通过电压无电流地读取和写入磁状态将提供巨大的技术优势。动态或光学 ME 效应同样有趣，因为它们导致单向光传播，如最近在低温多铁性体中观察到的那样。如果在室温下实现，这种现象将允许开发仅在一个方向而不在相反方向传输非偏振光的光二极管。在这里，我们报告了在室温多铁性 BiFeO_{3} 中在千兆赫兹至太赫兹频率范围内的强单向传输。支持该观察结果的理论将观察到的单向传输归因于自旋电流驱动的动态 ME 效应。这些发现朝着实现光二极管迈出了重要一步，并补充了通过磁场或电场切换传输方向的能力。
