Modification of the Magnetic and Electronic Properties of Ordered Arrays of (II, Mn)VI Quantum Wires Due to Reduced Lateral Dimensions
Modification of the Magnetic and Electronic Properties of Ordered Arrays of (II, Mn)VI Quantum Wires Due to Reduced Lateral Dimensions
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DOI：
10.1002/1521-3951(200201)229:1
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发表时间：
2002
影响因子：
1.6
通讯作者：
Limei Chen;H. Falk;P. Klar;W. Heimbrodt;F. Brieler;M. Fröba;H. K. Nidda;A. Loidl;Z. Chen;Y. Oka
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文献类型：
--
作者：
Limei Chen;H. Falk;P. Klar;W. Heimbrodt;F. Brieler;M. Fröba;H. K. Nidda;A. Loidl;Z. Chen;Y. Oka
通过将0 ≤ x ≤ 1的（II，Mn）VI半导体引入介孔MCM-41 SiO2基质的孔体系中，合成了横向尺寸为3 nm、间隔为2nmSiO 2的Cd 1-xMnxS和Cd 1-xMnxSe量子线的高度有序阵列.利用光致发光和光致发光激发光谱研究了在低温和高达7.5T的磁场下的电子和激子性质。由于导线中激子的量子限制，观察到（Cd，Mn）S的直接带隙增加了约200 meV，（Cd，Mn）Se的直接带隙增加了约350 meV。此外，我们观察到一个更强的，p-d杂化相关的带隙弯曲作为锰浓度的函数相比，散装线。这种效应与由于量子限制而导致的带隙的增加有关，量子限制使类p价带边缘更靠近价带中的Mn-3d相关态。令人惊讶的是，s，p-d交换诱导的巨大塞曼分裂的激子在（Cd，Mn）Se线相比，在散装材料似乎是非常小的。在2 ~ 300 K温度范围内，用SQUID和电子顺磁共振测量研究了样品的磁性。与体相（II，Mn）VI化合物相比，Mn 2+离子磁矩间的反铁磁耦合减弱，当x > 0.8时，Mn-体系的顺磁-反铁磁相变被抑制，这是因为线的横向尺寸小于反铁磁有序的磁长度尺度.
We present a novel way of synthesising highly ordered arrays of Cd 1-x Mn x S and Cd 1-x Mn x Se quantum wires with lateral dimensions of 3 nm separated by 2 nm SiO 2 barriers by incorporating the (II,Mn)VI semiconductor with 0 ≤ x ≤ 1 into the pore system of mesoporous MCM-41 SiO 2 matrices. The electronic and excitonic properties were studied using photoluminescence and photoluminescence excitation spectroscopy at low temperatures and in magnetic fields up to 7.5 T. Due to the quantum confinement of the excitons in the wires an increase of the direct band gap by about 200 meV for (Cd, Mn)S and by about 350 meV for (Cd, Mn)Se is observed. In addition, we observe a much stronger, p-d hybridisation related band gap bowing as a function of Mn-concentration in the wires compared to bulk. This effect is related to the increase of the band gap due to the quantum confinement which shifts the p-like valence band edge closer to the Mn-3d-related states in the valence band. Surprisingly, the s,p-d exchange induced giant Zeeman splitting of the excitons in the (Cd,Mn)Se wires compared to those in bulk material appears to be very small. The magnetic properties of the samples were studied by SQUID and electron paramagnetic resonance measurements in the temperature range from 2 to 300 K. Compared to the bulk (II, Mn)VI compounds, a reduced antiferromagnetic coupling between the magnetic moments of the Mn 2+ ions is found. For x > 0.8, a suppression of the paramagnetic to antiferromagnetic phase transition of the Mn-system is observed because the lateral dimensions of the wires are smaller than the magnetic length scale of the antiferromagnetic ordering.