Axion-Field-Enabled Nonreciprocal Thermal Radiation in Weyl Semimetals.
Axion-Field-Enabled Nonreciprocal Thermal Radiation in Weyl Semimetals.
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DOI：
10.1021/acs.nanolett.9b05179
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发表时间：
2019-11
期刊：
影响因子：
10.8
通讯作者：
B. Zhao;Cheng Guo;Christina A. C. Garcia;P. Narang;S. Fan
中科院分区：
文献类型：
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作者：
B. Zhao;Cheng Guo;Christina A. C. Garcia;P. Narang;S. Fan
我们周围的物体不断发射和吸收热辐射。发射和吸收过程由两个基本辐射特性控制：发射率和吸收率。对于互易系统，根据基尔霍夫热辐射定律，发射率和吸收率被限制为相等。这种限制限制了控制热辐射的自由度，并导致光子能量收集系统中的固有损耗机制。违反基尔霍夫定律的现有方法通常利用外部磁场的磁光效应。然而，这些方法需要强磁场（~3T）或中等磁场（~0.3T）下的窄带谐振，因为传统磁光效应的非互易性在热波长范围内很弱。在这里，我们证明磁性外尔半金属中的轴子电动力学可用于构造强不可逆热发射体，该热发射体在宽角度和频率范围内几乎完全违反基尔霍夫定律，而不需要任何外部磁场。
Objects around us constantly emit and absorb thermal radiation. The emission and absorption processes are governed by two fundamental radiative properties: emissivity and absorptivity. For reciprocal systems, the emissivity and absorptivity are restricted to be equal by Kirchhoff's law of thermal radiation. This restriction limits the degree of freedom to control thermal radiation and contributes to an intrinsic loss mechanism in photonic energy harvesting systems. Existing approaches to violate Kirchhoff's law typically utilize magneto-optical effects with an external magnetic field. However, these approaches require either a strong magnetic field (~3T), or narrow-band resonances under a moderate magnetic field (~0.3T), because the non-reciprocity in conventional magneto-optical effects is weak in the thermal wavelength range. Here, we show that the axion electrodynamics in magnetic Weyl semimetals can be used to construct strongly nonreciprocal thermal emitters that near completely violate Kirchhoff's law over broad angular and frequency ranges, without requiring any external magnetic field.