论文标题
$ \ MATHCAL {PT} $ - 对称磁性量量子材料中的巨型非线性光电流
Giant nonlinear photocurrent in $\mathcal{PT}$-symmetric magnetic topological quantum materials
论文作者
论文摘要
时间逆转不变的非中心对称系统的非线性光电流引起了很大的兴趣。在这里，我们提出了两种新型的二阶非线性直接光电流，作为正常移位光电流（NSC）和正常注射光电流（NIC）的对应物，即磁性移位光电流（MSC）和磁性喷射光电流（MIC）在时间逆向对称和反式对称性和反式对称性对称性中。我们表明，MSC主要由Shift Vector和Band Berry Inter Berry Curvature支配，MIC以吸收强度和群体速度差异的吸收强度和不对称性为主导。 MSC和MIC可以分别通过$ \ MATHCAL {PT} $ - 具有$ \ Mathcal {P} $和$ \ Mathcal {T} $的对称系统诱导。服用$ \ MATHCAL {PT} $ - 对称磁性量子量子材料双层抗铁磁性（AFM）MNBI $ _2 $ _2 $ TE $ _4 $作为例子，我们预测，在Terahertz频率方案中存在大型麦克风，可以在两个AFM之间具有磁性的AFM状态，并具有时间磁性稳定的序列。虽然NSC在$ \ Mathcal {t} $ - 对称系统中消失，但外部电场破坏了$ \ Mathcal {pt} $对称，并启用可以电气切换的大型NSC响应。麦克风和NSC在线性$ x $/$ y $偏振的光线下彼此垂直，并且在电场下高度可调，从而导致巨大的非线性光电流响应降至几个THZ制度。它建议BiLayer AFM MNBI $ _2 $ te $ _4 $作为具有丰富THZ和Magneto-OptoelectRonic应用程序的可调平台。目前的工作表明，非线性光电流为破译磁性结构和相互作用提供了强大的工具，特别是在探测和理解磁性拓扑量子材料方面尤其有效。
Nonlinear photocurrent in time-reversal invariant noncentrosymmetric systems have attracted substantial interest. Here we propose two new types of second-order nonlinear direct photocurrent as the counterpart of normal shift photocurrent (NSC) and normal injection photocurrent (NIC), namely magnetic shift photocurrent (MSC) and magnetic injection photocurrent (MIC) in time-reversal symmetry and inversion symmetry broken system. We show that MSC is mainly governed by shift vector and interband Berry curvature, and MIC is dominated by absorption strength and asymmetry of the group velocity difference at time-reversed $\pm$$\textbf{k}$ points. MSC and MIC can be induced by circularly and linearly polarized light, respectively, in $\mathcal{PT}$-symmetric systems with $\mathcal{P}$ and $\mathcal{T}$ being individually broken. Taking $\mathcal{PT}$-symmetric magnetic topological quantum material bilayer antiferromagnetic (AFM) MnBi$_2$Te$_4$ as an example, we predict the presence of large MIC in the terahertz frequency regime which can be magnetically switched between two AFM states with time-reversed spin orderings. While NSC vanishes in $\mathcal{T}$-symmetric systems, external electric field breaks $\mathcal{PT}$ symmetry and enables large NSC response which can be electrically switched. MIC and NSC are perpendicular to each other upon linearly $x$/$y$-polarized light, and are highly tunable under electric field, resulting in giant nonlinear photocurrent response down to a few THz regime. It suggests bilayer AFM MnBi$_2$Te$_4$ as a tunable platform with rich THz and magneto-optoelectronic applications. The present work reveals that nonlinear photocurrent provides a powerful tool for deciphering magnetic structures and interactions, particularly fruitful for probing and understanding magnetic topological quantum materials.
