AI 中文总结
研究核自旋稀释CeO₂中由空位诱导的Ce³⁺自旋中心，采用第一性原理计算等方法，考虑四种空位构型，确定其超精细结构和交换耦合，为评估自旋相干性质提供第一性原理磁参数，确立其为核自旋稀释宿主。
AI 中文摘要
氧化铈CeO₂中的氧空位提供电子，这些电子定域为Ce³⁺（4f¹，S = 1/2）小极化子，通过本征缺陷化学而非注入或非本征掺杂形成稀土自旋中心。我们使用具有线性响应哈伯德参数（U = 5.8382 eV）的第一性原理PBE + U计算、投影增强波方法的全电子重构得到的超精细张量以及相干势近似下的Korringa - Kohn - Rostoker交换计算来研究这些中心的磁环境。考虑了四种浓度范围从3.125%到12.5%的空位构型。宿主的一个显著特征源于铈同位素：所有天然存在的铈同位素核自旋I = 0，消除了Ce³⁺中心的局域超精细相互作用，使核自旋浴完全位于氧亚晶格上，其唯一的磁性同位素¹⁷O（I = 5/2）天然丰度为0.038%。由此产生的¹⁷O超精细景观由少量强耦合、近轴向的第一壳层原子核组成，接触耦合达到6 MHz，周围是弱耦合且强各向异性的外壳层。这些张量为¹⁷O电子自旋回波包络调制（ESEEM）和高分辨超精细相互作用谱（HYSCORE）测量定义了实验可获取的特征，并为自旋相干的团簇关联展开计算提供了微观超精细参数。相邻极化子之间的交换相互作用较弱且由氧介导，在所考虑的浓度范围内，空位产生的自旋基本独立。这些结果共同确立了缺氧CeO₂作为一种化学生成且本质上核自旋稀释的稀土自旋中心宿主，并提供了评估其相干性质所需的第一性原理磁参数。
英文摘要
Oxygen vacancies in ceria CeO$_2$ donate electrons that localize as Ce$^{3+}$ ($4f^1$, $S=1/2$) small polarons, creating rare-earth spin centers through native defect chemistry rather than implantation or extrinsic doping. We investigate the magnetic environment of these centers using first-principles PBE$+U$ calculations with a linear-response Hubbard parameter ($U=5.8382$ eV), hyperfine tensors from the all-electron reconstruction of the projector-augmented-wave method, and Korringa-Kohn-Rostoker exchange calculations within the coherent-potential approximation. Four vacancy configurations spanning concentrations from $3.125\%$ to $12.5\%$ are considered. A distinctive feature of the host follows from cerium isotopics: all naturally occurring cerium isotopes possess nuclear spin $I=0$, eliminating on-site hyperfine interactions at the Ce$^{3+}$ center and leaving the nuclear-spin bath entirely on the oxygen sublattice, whose sole magnetic isotope, $^{17}O$ ($I=5/2$), occurs at $0.038\%$ natural abundance. The resulting $^{17}O$ hyperfine landscape consists of a small number of strongly coupled, nearly axial first-shell nuclei with contact couplings reaching $6$~MHz, surrounded by a weakly coupled and strongly anisotropic outer shell. These tensors define experimentally accessible signatures for $^{17}O$ ESEEM and HYSCORE measurements and provide the microscopic hyperfine parameters required for cluster-correlation-expansion calculations of spin coherence. Exchange interactions between neighboring polarons are weak and oxygen-mediated, leaving the vacancy-generated spins largely independent over the concentration range considered. Together, these results establish oxygen-deficient CeO$_2$ as a chemically generated and intrinsically nuclear-spin-dilute host for rare-earth spin centers, and provide the first-principles magnetic parameters needed to assess their coherence properties.
Comments11 pages, 8 figures
