石墨烯中的非厄米杂质散射：玻尔兹曼输运与热电响应
Non-Hermitian impurity scattering in graphene: Boltzmann transport and thermoelectric response
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中文总结 AI 辅助
本文研究石墨烯中非厄米杂质散射对热电输运的影响，通过分波法求解狄拉克散射并构建玻尔兹曼模型，发现增益增强而损失抑制热电性能，为调控石墨烯热电响应提供新机制。
中文摘要 AI 辅助
我们研究了含有稀疏散布有限程非厄米散射中心的单层石墨烯中的电荷和热电输运。杂质被建模为圆形复势，其虚部描述了局部的载流子损失或增益。通过分波方法精确求解狄拉克散射问题，我们获得了非幺正散射矩阵，并推导了输运和吸收截面，它们分别表征了动量弛豫和与环境的净载流子交换。为了将微观散射问题与稳态输运联系起来，我们构建了一个半经典的玻尔兹曼描述，其中外部储库补偿了平衡态的粒子损失或增益。这导致了一个有效的弛豫时间，该时间由弹性动量散射和非厄米通量交换共同决定。利用完整的能量依赖弛豫时间，我们评估了昂萨格系数以及由此产生的电导率、电子热导率、塞贝克系数、洛伦兹比和电子热电优值。我们发现，弱增益增加了有效载流子寿命，并增强了电荷和热导率，而吸收则产生相反的行为。更重要的是，增益增强了热电势和电子优值的幅度，而损失则抑制了它们。洛伦兹比保持接近索末菲值，非厄米性主要修改了其有限温度修正。我们的结果表明，非厄米散射为控制载流子弛豫的能量依赖性以及石墨烯的热电响应提供了一种额外的机制。
英文摘要
We investigate charge and thermoelectric transport in monolayer graphene containing a dilute distribution of finite-range non-Hermitian scattering centers. The impurities are modeled as circular complex potentials, whose imaginary component describes local carrier loss or gain. By solving the Dirac scattering problem exactly within a partial-wave approach, we obtain the nonunitary scattering matrix and derive the transport and absorption cross sections, which separately characterize momentum relaxation and net carrier exchange with the environment. To connect the microscopic scattering problem with stationary transport, we formulate a semiclassical Boltzmann description in which an external reservoir compensates the equilibrium particle loss or gain. This leads to an effective relaxation time governed by both elastic momentum scattering and non-Hermitian flux exchange. Using the full energy-dependent relaxation time, we evaluate the Onsager coefficients and the resulting electrical conductivity, electronic thermal conductivity, Seebeck coefficient, Lorenz ratio, and electronic thermoelectric figure of merit. We find that weak gain increases the effective carrier lifetime and enhances both charge and heat conductivities, while absorption produces the opposite behavior. More importantly, gain enhances the magnitude of the thermopower and the electronic figure of merit, whereas loss suppresses them. The Lorenz ratio remains close to the Sommerfeld value, with non-Hermiticity mainly modifying its finite-temperature corrections. Our results show that non-Hermitian scattering provides an additional mechanism for controlling the energy dependence of carrier relaxation and, consequently, the thermoelectric response of graphene.
发表机构
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México（墨西哥国立自治大学核科学研究所）
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