Electron Spin Coherence of Shallow Donors in Natural and Isotopically Enriched Germanium
Electron Spin Coherence of Shallow Donors in Natural and Isotopically Enriched Germanium
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DOI：
10.1103/physrevlett.115.247601
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发表时间：
2015-12-07
影响因子：
8.6
通讯作者：
Lyon, S. A.
中科院分区：
文献类型：
--
作者：
Sigillito, A. J.;Jock, R. M.;Lyon, S. A.
锗是一种广泛应用于电子和光电子器件的材料，近年来已成为自旋电子学和量子计算应用的重要材料。硅中的供体自旋已被证明支持非常长的相干时间（T-2），当宿主材料同位素富集以去除任何磁性原子核时。锗也有非磁性同位素，所以它有望支持长T-2，同时提供一些新的性质。与Si相比，Ge具有强的自旋轨道耦合、大的电子波函数、高迁移率和高各向异性的传导带谷，这些都将产生新的物理学。本文介绍了天然锗和同位素富集锗中As-75和P-31给体的第一次脉冲电子自旋共振T-2和自旋晶格弛豫（T-1）时间。我们比较了不同同位素富集水平的样品，发现由于Ge-73核自旋引起的光谱扩散限制了大量Ge-73样品的相干性。对于富集程度最高的样品，我们发现T-1限制T-2至T-2 = 2T(1)。我们报告了T-1的各向异性和沿不同晶体轴取向的磁场的系综线宽，但没有解决任何角度依赖于锗-73样品中光谱扩散限制的T-2。
Germanium is a widely used material for electronic and optoelectronic devices and recently it has become an important material for spintronics and quantum computing applications. Donor spins in silicon have been shown to support very long coherence times (T-2) when the host material is isotopically enriched to remove any magnetic nuclei. Germanium also has nonmagnetic isotopes so it is expected to support long T-2's while offering some new properties. Compared to Si, Ge has a strong spin-orbit coupling, large electron wave function, high mobility, and highly anisotropic conduction band valleys which will all give rise to new physics. In this Letter, the first pulsed electron spin resonance measurements of T-2 and the spin-lattice relaxation (T-1) times for As-75 and P-31 donors in natural and isotopically enriched germanium are presented. We compare samples with various levels of isotopic enrichment and find that spectral diffusion due to Ge-73 nuclear spins limits the coherence in samples with significant amounts of Ge-73. For the most highly enriched samples, we find that T-1 limits T-2 to T-2 = 2T(1). We report an anisotropy in T-1 and the ensemble linewidths for magnetic fields oriented along different crystal axes but do not resolve any angular dependence to the spectral-diffusion-limited T-2 in samples with Ge-73.