标题： 磁掺杂Cd$_3$As$_2$中的单极超导性 显示英文标题

标题： Monopole Superconductivity in Magnetically Doped Cd$_3$As$_2$

摘要： 当具有不同陈数的费米面之间发生超导配对时，库珀对具有非平凡的对贝里相位，这强制导致配对能隙节点。这种产生的配对序与常见的$s$-、$p$- 和$d$- 波配对序不同，因为它具有非零的对单极电荷，并由单极谐函数描述。迄今为止，这种奇特的单极配对序尚未在实验中实现。因此，我们研究磁掺杂的狄拉克半金属 Cd$_3$As$_2$作为实现具有对单极电荷$q_p=1$或$2$的单极超导性的候选材料，具体取决于化学势。 对于每种偶极子电荷的情况，我们研究了磁掺杂Cd$_3$As$_2$的$C_{4h}$对称性所有允许的不可约表示中的均匀配对序的代表。 我们展示了由于高陈数拓扑费米面和晶体对称性的结合而产生的不同高阶部分波超导序的偶极子类似物之间的差异。 在所有情况下，费米面上超导相位绕行的模式受到拓扑不变的总绕行数的约束，该数仅取决于偶极子电荷，并要求$q_p\neq 0$超导序中存在节点。 我们的工作可以指导对拓扑半金属Cd$_3$As$_2$中偶极子序的进一步实验研究，并且可以推广到其他具有高陈数费米面的材料，这些材料在高阶部分波中强制偶极子配对序，例如$f$-波配对的偶极子类似物。 显示英文摘要

摘要： When superconducting pairing occurs between Fermi surfaces with different Chern numbers, the Cooper pairs possess nontrivial pair Berry phase, which enforces pairing gap nodes. The resulting pairing order is further distinguished from the familiar $s$-, $p$-, and $d$-wave pairing orders by a nonzero pair monopole charge and is described by monopole harmonics. To date, this exotic monopole pairing order is yet to be achieved experimentally. We therefore study the magnetically doped Dirac semimetal Cd$_3$As$_2$ as a candidate material for realizing monopole superconductivity with pair monopole charges $q_p=1$ or $2$, depending on the chemical potential. For each case of pair monopole charge, we explore representatives of uniform pairing orders in all allowed irreducible representations of the $C_{4h}$ symmetry of magnetically doped Cd$_3$As$_2$. We demonstrate the distinctions in the monopole analogs of different higher partial wave superconducting orders that result from the combination of topological Fermi surfaces of higher Chern number and crystalline symmetry. In all cases, the patterns of the superconducting phase winding around a Fermi surface are constrained by the topologically invariant total winding number, which depends only on the pair monopole charge and requires nodes in the $q_p\neq 0$ superconducting order. Our work can guide further experimental investigation of monopole orders in the topological semimetal Cd$_3$As$_2$ and can be generalized to other materials with Fermi surfaces of higher Chern number, which enforce monopole pairing order in higher partial waves, such as the monopole analog of $f$-wave pairing.