Absorption and Magnetic Circular Dichroism Analyses of Giant Zeeman Splittings in Diffusion-Doped Colloidal Cd1–xMnxSe Quantum Dots,The Journal of Physical Chemistry Letters

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Absorption and Magnetic Circular Dichroism Analyses of Giant Zeeman Splittings in Diffusion-Doped Colloidal Cd1–xMnxSe Quantum Dots
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2015-07-23 00:00:00 , DOI: 10.1021/acs.jpclett.5b01137
Charles J. Barrows ₁ , Vladimir A. Vlaskin ₁ , Daniel R. Gamelin ₁

Affiliation

Impurity ions can transform the electronic, magnetic, or optical properties of colloidal quantum dots. Magnetic impurities introduce strong dopant-carrier exchange coupling that generates giant Zeeman splittings (ΔE_Z) of excitonic excited states. To date, ΔE_Z in colloidal doped quantum dots has primarily been quantified by analysis of magnetic circular dichroism (MCD) intensities and absorption line widths (σ). Here, we report ΔE_Z values detected directly by absorption spectroscopy for the first time in such materials, using colloidal Cd_1–xMn_xSe quantum dots prepared by diffusion doping. A convenient method for decomposing MCD and absorption data into circularly polarized absorption spectra is presented. These data confirm the widely applied MCD analysis in the low-field, high-temperature regime, but also reveal a breakdown at low temperatures and high fields when ΔE_Z/σ approaches unity, a situation not previously encountered in doped quantum dots. This breakdown is apparent for the first time here because of the extraordinarily large ΔE_Z and small σ achieved by nanocrystal diffusion doping.

中文翻译：

扩散掺杂胶体Cd _{1– x} Mn _x Se量子点中巨型塞曼分裂的吸收和电磁圆二色性分析

杂质离子可以改变胶体量子点的电子，磁性或光学性质。磁性杂质会引入强的掺杂剂-载流子交换耦合，从而产生激子激发态的巨大塞曼分裂（ΔE _Z）。迄今为止，胶体掺杂量子点中的ΔE _Z主要是通过分析磁性圆二色性（MCD）强度和吸收线宽度（σ）来量化的。在这里，我们报告了使用胶态Cd _1–_x Mn _x首次在这种材料中通过吸收光谱法直接检测到的ΔE _Z值通过扩散掺杂制备的Se量子点。提出了一种方便的方法来将MCD和吸收数据分解为圆偏振吸收光谱。这些数据证实了在低温，高温状态下广泛应用的MCD分析，但同时揭示了当ΔE _Z /σ接近1时在低温和高场下的击穿现象，这种情况以前在掺杂量子点中没有遇到过。这种击穿在这里是第一次明显，因为通过纳米晶体扩散掺杂获得了非常大的ΔE _Z和小的σ。

更新日期：2015-07-23

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