论文标题
DYPC $ _2 $分子的Hyperfine和四极杆相互作用
Hyperfine and quadrupole interactions for Dy isotopes in DyPc$_2$ molecules
论文作者
论文摘要
核自旋水平在理解磁化动力学以及基于兰烷基的单分子磁体中的量子位的实现和控制方面起着重要作用。我们研究了$^{161} $ dy和$^{163} $ dy nucleus在阴离子DYPC $ _2 $（PC =苯二苯胺）单分子磁体中的超精细和核四极的相互作用，使用多核电abinitio方法（超越密度 - 函数函数函数的理论），包括旋转式的Interaction。选择DY的两个同位素是因为其他同位素的核自旋为零。两种同位素都有核自旋$ i = 5/2 $，尽管核磁矩的幅度和迹象彼此不同。电子地面和首选的Kramers Doublet之间的较大能量鸿沟，使我们能够将微观超精美和四极相互作用hamiltonian映射到有效的哈密顿量上，带有电子伪旋转$ s _ {\ rm eff} = 1/2 $，与地面kramers doublet doublet。我们的AB-INITIO计算表明，核自旋和电子轨道角动量之间的耦合对超精细的相互作用贡献最大，并且对于$^{161} $ dy和$^{163} $ dy nucleus的超精和核四极相互作用都比$^$^159 $ tb $ tb $ tb nucc $ tb nucc $ tb nucc $ tb nucc $ tb nucc。电子 - 核级别的计算分离与报告的实验数据相当，以$^{163} $ DYPC $ _2 $。我们证明，Dy Kramers离子的超细相互作用会导致零场处的隧道分裂（或磁化的量子隧穿）。 TBPC $ _2 $单分子磁铁不会发生这种效果。 $^{161} $ dypc $ _2 $和$^{163} $ dypc $ _2 $的磁场值避免了级别的交叉点，发现可以从实验中观察到。
Nuclear spin levels play an important role in understanding magnetization dynamics and implementation and control of quantum bits in lanthanide-based single-molecule magnets. We investigate the hyperfine and nuclear quadrupole interactions for $^{161}$Dy and $^{163}$Dy nucleus in anionic DyPc$_2$ (Pc=phthalocyanine) single-molecule magnets, using multiconfigurational ab-initio methods (beyond density-functional theory) including spin-orbit interaction. The two isotopes of Dy are chosen because the others have zero nuclear spin. Both isotopes have the nuclear spin $I=5/2$, although the magnitude and sign of the nuclear magnetic moment differ from each other. The large energy gap between the electronic ground and first-excited Kramers doublets, allows us to map the microscopic hyperfine and quadrupole interaction Hamiltonian onto an effective Hamiltonian with an electronic pseudo-spin $S_{\rm eff}=1/2$ that corresponds to the ground Kramers doublet. Our ab-initio calculations show that the coupling between the nuclear spin and electronic orbital angular momentum contributes the most to the hyperfine interaction and that both the hyperfine and nuclear quadrupole interactions for $^{161}$Dy and $^{163}$Dy nucleus are much smaller than those for $^{159}$Tb nucleus in TbPc$_2$ single-molecule magnets. The calculated separations of the electronic-nuclear levels are comparable to experimental data reported for $^{163}$DyPc$_2$. We demonstrate that hyperfine interaction for Dy Kramers ion leads to tunnel splitting (or quantum tunneling of magnetization) at zero field. This effect does not occur for TbPc$_2$ single-molecule magnets. The magnetic field values of the avoided level crossings for $^{161}$DyPc$_2$ and $^{163}$DyPc$_2$ are found to be noticeably different, which can be observed from experiment.
