The recent accessibility of high-quality, charge-neutral monolayer transition metal dichalcogenides with narrow exciton linewidths at the homogeneous limit provides an ideal platform to study excitonic many-body interactions. In particular, the possibility to manipulate coherent exciton-exciton interactions, which govern the ultrafast nonlinear optical response, by applying an external magnetic field has not been considered so far. We address this discrepancy by presenting a nonlinear microscopic theory in the coherent limit for optical excitations in the presence of out-of-plane, in-plane, and tilted magnetic fields. Specifically, we explore the magnetic-field-induced exciton and biexciton fine structure and calculate their oscillator strengths based on a Heisenberg equations-of-motion formalism. Our microscopic evaluations of pump-probe spectra allow to interpret and predict coherent signatures in future wave-mixing experiments.

中文翻译：

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单层过渡金属硫族化合物中磁激子和双激子相干响应的理论

高质量的，电荷中性的单层过渡金属二金属二硫化物的最新可及性，其激子线宽在均相极限处较窄，为研究激子多体相互作用提供了理想的平台。特别地，到目前为止，尚未考虑通过施加外部磁场来操纵控制超快速非线性光学响应的​​相干激子-激子相互作用的可能性。我们通过在存在平面外，平面内和倾斜磁场的情况下对光学激发的相干极限提出非线性微观理论来解决这一差异。具体来说，我们探索磁场引起的激子和双激子的精细结构，并根据海森堡运动方程形式来计算其振动强度。