Transition metal disulfides $4H_b$-Ta(S, ${\mathrm{Se})}_2$ with natural heterostructure of $1T$- and $1H$-Ta(S, ${\mathrm{Se})}_2$ layers have became the focus of correlated materials their unique combinations of Mott physics and possible topological superconductivity. In this work, we study the upper critical fields ${\mu }_0{H}_{c2}$ of $4H_b\text{−}{\mathrm{TaS}}_2$ and $4H_b\text{−}{\mathrm{TaS}}_{1.99}{\mathrm{Se}}_{0.01}$ single crystals systematically. Transport measurements up to 35 T show that both of $ab$-plane and $c$-axis upper critical fields (${\mu }_0{H}_{c2,ab}$ and ${\mu }_0{H}_{c2,c}$) for $4H_b\text{−}{\mathrm{TaS}}_2$ and $4H_b\text{−}{\mathrm{TaS}}_{1.99}{\mathrm{Se}}_{0.01}$ exhibit a linear temperature dependent behavior down to 0.3 K, suggesting the three-dimensional superconductivity with dominant orbital depairing mechanism in bulk $4H_b$-Ta(S, ${\mathrm{Se})}_2$. However, the zero-temperature ${\mu }_0{H}_{c2,ab}$(0) for both crystals are far beyond the Pauli paramagnetic limit ${\mu }_{0}H{}_{\mathrm{P}}$. It could be explained by the effects of spin-momentum locking in $1H$-Ta(S, ${\mathrm{Se})}_2$ layers with local inversion symmetry broken and the relatively weak intersublattice interaction between $1H$ layers due to the existence of $1T$ layers.

中文翻译：

---

4Hb−Ta(S,Se)2 块体晶体中极端轨道实验室平面上临界场远远超出泡利极限

过渡金属二硫化物$4H_{乙}$-Ta(S,${硒）}_2$具有天然异质结构$1\mathrm{时间}$- 和$1H$-Ta(S,${硒）}_2$层已成为相关材料的焦点，它们是莫特物理学和可能的拓扑超导性的独特组合。在这项工作中，我们研究上临界场${\mu }_0{H}_{C2}$的$4H_{乙}\text{-}{\mathrm{硫化钽}}_2$和$4H_{乙}\text{-}{\mathrm{硫化钽}}_{1.99}{硒}_{0.01}$系统地制备单晶。高达 35 T 的传输测量表明$A乙$-平面和$C$-轴上临界场（${\mu }_0{H}_{C2,A乙}$和${\mu }_0{H}_{C2,C}$） 为了$4H_{乙}\text{-}{\mathrm{硫化钽}}_2$和$4H_{乙}\text{-}{\mathrm{硫化钽}}_{1.99}{硒}_{0.01}$表现出低至 0.3 K 的线性温度依赖性行为，表明三维超导性具有主要的轨道脱对机制$4H_{乙}$-Ta(S,${硒）}_2$。然而，零温${\mu }_0{H}_{C2,A乙}$(0) 两种晶体都远远超出泡利顺磁极限${\mu }_{0}H{}_{\mathrm{磷}}$。这可以通过自旋动量锁定的效应来解释$1H$-Ta(S,${硒）}_2$局部反演对称性破缺的层以及子晶格间相对较弱的相互作用$1H$由于层的存在$1\mathrm{时间}$层。