非幺正态中轨道退对极限的破缺——关于重费米子超导体 UTe$_2$ 中高场相的研究
Violation of the orbital depairing limit in a non-unitary state --on the high field phase in the heavy Fermion superconductor UTe$_2$--
AI总结：
本文基于 Ginzburg-Landau 框架研究 UTe$_2$ 极高上临界场起源，指出自旋三重态非幺正态与底层磁化耦合可破缺轨道退对极限，为纯净超导体高场物理提供了完整框架。
摘要：
本文对 UTe$_2$ 中观察到的极高上临界场（约 70T）的起源进行了理论研究，其转变温度 T$_{rm c}$=1.6K-2K，远超处于纯净极限下的超导体（SC）由费米速度和 T$_{rm c}$ 设定的常规轨道退对极限。我们基于自旋三重态非幺正态研究了轨道极限可能的破缺，该状态与外部场感应的底层磁化强度有效耦合。这反过来通过磁化强度抵消内部场，从而产生降低的内部场。我们在 Ginzburg-Landau 框架内构建理论来描述这种轨道极限破缺，并分析了 UTe$_2$ 中各种磁场取向下上临界场的实验数据。我们指出，自旋三重态 SC 的轨道极限破缺与自旋单态 SC 的 Pauli-Clogston 极限破缺共同构成了一个完整且有用的框架，用于检验纯净极限下超导体的高场物理。
英文摘要：
A theoretical study is reported on the origin of extremely high upper critical field $\sim$70T observed in UTe$_2$ with the transition temperature T$_{\rm c}$=1.6K-2K, far exceeding the conventional orbital depairing limit set by the Fermi velocity and T$_{\rm c}$ for a superconductor (SC) in the clean limit. We investigate possible violation of the orbital limit in terms of a spin-triplet nonunitary state, which is effectively coupled to the underlying magnetization induced by external field. This in turn produces the reduced internal field by cancelling it via magnetization. We formulate a theory within Ginzburg-Landau framework to describe this orbital limit violation and analyze experimental data on the upper critical fields for various field orientations in UTe$_2$. It is pointed out that the orbital limit violation for a spin-triplet SC together with the Pauli-Clogston limit violation for a spin-singlet SC constitutes a complete and useful framework to examine the high field physics in superconductors in the clean limit.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
