标题： 单晶钨酸钙的介电性能 显示英文标题

标题： Dielectric Properties of Single Crystal Calcium Tungstate

摘要： 这项研究采用了微波耳语画廊模式（WGM）分析来表征钨酸钙（CaWO$_4$）圆柱形单晶样品的介电特性。 通过研究准横磁\hyp{}和准横电\hyp{}模式族，我们可以从室温到低温条件评估损耗机制和相对介电常数。 我们报告$\epsilon_{||} = 9.029 \pm 0.09$和$\epsilon_{\perp} = 10.761 \pm 0.11$在$295$K 时的双轴介电常数值，以及$\epsilon_{||} = 8.797 \pm 0.088$和$\epsilon_{\perp} = 10.442 \pm 0.104$在$4$K 时的双轴介电常数值。各分量是相对于晶体晶胞的 c\hyp{}轴来表示的。 平行分量在MHz频率下与已发表的文献一致；然而，垂直分量低了$4.8$%。 WGM技术提供了更高的精度，其准确性主要受限于晶体尺寸的不确定性。 WGM also serve as sensitive probes of lattice dynamics, enabling monitoring of temperature-dependent loss mechanisms. 在室温下，测得的损耗正切分别为$\tan\delta_{||}^{295,\mathrm{K}} = (4.1 \pm 1.4) \times 10^{-5}$和$\tan\delta_{\perp}^{295,\mathrm{K}} = (3.64 \pm 0.92) \times 10^{-5}$。 冷却至4 K时，损耗正切提高了约两个数量级，达到$\tan\delta_{||}^{4,\mathrm{K}} = (1.56 \pm 0.52) \times 10^{-7}$和$\tan\delta_{\perp}^{4,\mathrm{K}} = (2.05 \pm 0.79) \times 10^{-7}$。 这些低温值高于之前研究中报道的值，可能是由于与未识别的顺磁自旋集合相关的磁损耗通道。 这些发现对CaWO$_4$在基于自旋的量子系统和低温测热计等应用中的使用具有重要意义，突显了WGM在新型传感应用中的潜力。 显示英文摘要

摘要： This investigation employed microwave whispering gallery mode (WGM) analysis to characterize the dielectric properties of a cylindrical, single-crystal sample of calcium tungstate (CaWO$_4$). Through investigation of quasi-transverse\hyp{}magnetic and quasi-transverse\hyp{}electric mode families, we can assess loss mechanisms and relative permittivity from room temperature down to cryogenic conditions. We report the biaxial permittivity values of $\epsilon_{||} = 9.029 \pm 0.09$ and $\epsilon_{\perp} = 10.761 \pm 0.11$ at $295$ K, and $\epsilon_{||} = 8.797 \pm 0.088$ and $\epsilon_{\perp} = 10.442 \pm 0.104$ at $4$ K. Components are denoted with respect to the c\hyp{}axis of the crystal unit cell. The parallel component agrees well with the published literature at MHz frequencies; however, the perpendicular component is $4.8$\% lower. The WGM technique offers greater precision, with accuracy limited primarily by the uncertainty in the crystal's dimensions. WGMs also serve as sensitive probes of lattice dynamics, enabling monitoring of temperature-dependent loss mechanisms. At room temperature, the measured loss tangents were $\tan\delta_{||}^{295,\mathrm{K}} = (4.1 \pm 1.4) \times 10^{-5}$ and $\tan\delta_{\perp}^{295,\mathrm{K}} = (3.64 \pm 0.92) \times 10^{-5}$. Upon cooling to 4 K, the loss tangents improved by approximately two orders of magnitude, reaching $\tan\delta_{||}^{4,\mathrm{K}} = (1.56 \pm 0.52) \times 10^{-7}$ and $\tan\delta_{\perp}^{4,\mathrm{K}} = (2.05 \pm 0.79) \times 10^{-7}$. These cryogenic values are higher than those reported in prior studies, likely due to a magnetic loss channel associated with an unidentified paramagnetic spin ensemble. These findings have implications for the use of CaWO$_4$ in applications such as spin-based quantum systems and cryogenic bolometry, highlighting the potential of WGMs for novel sensing applications.