发表机构
Chimie ParisTech, PSL University; CNRS, Institut de Recherche de Chimie Paris（巴黎高等化学学院，PSL大学; 法国国家科学研究中心，巴黎化学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过EPR精确测定CaWO$_4$中Dy$^{3+}$的g因子和超精细常数，结合晶场分析识别基态双重态来源，并首次测得线性电场耦合参数，揭示内电场展宽机制。
AI 中文摘要
我们报道了在掺杂浓度从80 ppb到247 ppm范围内，CaWO$_4$单晶中Dy${^3+}$的电子顺磁共振（EPR）研究。在$S_4$点群位点处基态Kramers双重态的$g$因子，$g_\parallel = 7.22 \pm 0.01$和$g_\perp = 5.45 \pm 0.01$，以及\ce{^{161}Dy}和$^{163}$Dy的超精细常数，其精度比之前唯一报道提高了一个数量级。由已发表的光学能级和测量的$g$张量共同约束的晶场分析，将基态双重态识别为近简并的$\\|{\pm}11/2>$和$\\|{\mp}13/2>$态之间反交叉的下支，并解释了为何仅光学数据无法约束$g$值。同一参数集在$^6H$项的激发多重态上测试，再现了${}^6H_{13/2}$晶场能级，其效果优于光学参数本身。$ab$平面内线宽的角依赖性揭示了通过线性电场效应由随机内电场引起的展宽。用同一晶体中残留的Er$^{3+}$校准这些电场，得到了Dy$^3+$的首个电场耦合参数，$(B_{31}^2+B_{36}^2)^{1/2} = (34\pm5)\times10^{-6}$~cm/V，是Er$^{3+}$值的三倍，也是稀土离子在该基质中报道的最大值。残余线宽和浓度依赖的线形不对称性遵循二阶斯塔克位移预期的二次方电场标度，该位移避开了约束线性效应的反演位点抵消。两种耦合都追溯到与第一相反宇称双重态约$20$~cm$^{-1}$的能隙，这是$J=15/2$流形密集晶场结构的结果。
英文摘要
We report an electron paramagnetic resonance (EPR) study of Dy${^3+}$ in CaWO$_4$ single crystals spanning dopant concentrations from 80~ppb to 247~ppm. The $g$ factors of the ground Kramers doublet at the $S_4$ point-group site, $g_\parallel = 7.22 \pm 0.01$ and $g_\perp = 5.45 \pm 0.01$, and the hyperfine constants of \ce{^{161}Dy} and $^{163}$Dy are determined with an order-of-magnitude improvement in precision over the only previous report. A crystal-field analysis constrained jointly by published optical levels and by the measured $g$ tensor identifies the ground doublet as the lower branch of an anticrossing between the near-degenerate $\|{\pm}11/2>$ and $\|{\mp}13/2>$ states, and explains why optical data alone left the $g$ values unconstrained. \add{The same parameter set, tested on the excited multiplets of the $^6H$ term, reproduces the ${}^6H_{13/2}$ crystal-field levels better than the optical parameters themselves.} The angular dependence of the linewidth in the $ab$ plane reveals broadening by random internal electric fields through the linear electric field effect. Calibrating these fields with the residual Er$^{3+}$ present in the same crystals yields the first electric-field coupling parameters of Dy$^3+$, $(B_{31}^2+B_{36}^2)^{1/2} = (34\pm5)\times10^{-6}$~cm/V, three times the Er$^{3+}$ value and the largest reported for a rare-earth ion in this host.The residual linewidth and the concentration-dependent lineshape asymmetry follow the quadratic field scaling expected for a second-order Stark shift, which escapes the inversion-site cancellation constraining the linear effect. Both couplings trace back to the $\sim 20$~cm$^{-1}$ gap to the first opposite-symmetry doublet, a consequence of the dense crystal-field structure of the $J=15/2$ manifold.
