Dehnel Joanna, Barak Yahel, Meir Itay, Budniak Adam K, Nagvenkar Anjani P, Gamelin Daniel R, Lifshitz Efrat
Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Department of Chemistry and the Molecular Engineering Materials Center, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States.
ACS Nano. 2020 Oct 27;14(10):13478-13490. doi: 10.1021/acsnano.0c05454. Epub 2020 Sep 25.
Controlling the spin degrees of freedom of photogenerated species in semiconductor nanostructures magnetic doping is an emerging scientific field that may play an important role in the development of new spin-based technologies. The current work explores spin properties in colloidal CdSe/CdS:Mn seeded-nanorod structures doped with a dilute concentration of Mn ions across the rods. The spin properties were determined using optically detected magnetic resonance (ODMR) spectroscopy recorded under variable microwave chopping frequencies. These experiments enabled the deconvolution of a few different radiative recombination processes: band-to-band, trap-to-band, and trap-to-trap emission. The results uncovered the major role of carrier trapping on the spin properties of elongated structures. The magnetic parameters, determined through spin-Hamiltonian simulation of the steady-state ODMR spectra, reflect anisotropy associated with carrier trapping at the seed/rod interface. These observations unveiled changes in the carriers' -factors and spin-exchange coupling constants as well as extension of radiative and spin-lattice relaxation times due to magnetic coupling between interface carriers and neighboring Mn ions. Overall, this work highlights that the spin degrees of freedom in seeded nanorods are governed by interfacial trapping and can be further manipulated by magnetic doping. These results provide insights into anisotropic nanostructure spin properties relevant to future spin-based technologies.
控制半导体纳米结构中光生载流子的自旋自由度——磁掺杂是一个新兴的科学领域，可能在新型自旋基技术的发展中发挥重要作用。当前的工作探索了在整个棒中掺杂稀浓度锰离子的胶体CdSe/CdS:Mn籽晶纳米棒结构中的自旋特性。自旋特性是通过在可变微波斩波频率下记录的光探测磁共振（ODMR）光谱来确定的。这些实验能够对几种不同的辐射复合过程进行反卷积：带间、陷阱到带以及陷阱到陷阱发射。结果揭示了载流子俘获对细长结构自旋特性的主要作用。通过对稳态ODMR光谱进行自旋哈密顿模拟确定的磁参数，反映了与籽晶/棒界面处载流子俘获相关的各向异性。这些观察结果揭示了载流子g因子和自旋交换耦合常数的变化，以及由于界面载流子与相邻锰离子之间的磁耦合导致的辐射和自旋晶格弛豫时间的延长。总体而言，这项工作强调了籽晶纳米棒中的自旋自由度受界面俘获支配，并且可以通过磁掺杂进一步调控。这些结果为与未来自旋基技术相关的各向异性纳米结构自旋特性提供了见解。
