近日，美国伊利诺伊大学香槟分校的Vidya Madhavan及其研究团队取得一项新进展。经过不懈努力，他们揭示UTe2中通过产生拓扑缺陷对的电荷密度波熔化过程。相关研究成果已于2024年3月20日在国际知名学术期刊《自然—物理学》上发表。
本文证明了拓扑缺陷在重费米子超导体UTe2中磁场诱导电荷密度波消失中的作用。研究人员揭示了正负相绕组电荷密度波的一对拓扑缺陷。这些电荷对与电荷密度波振幅的零点有着直接的关联，并且会随着磁场的增强而增加。磁场不仅能产生超导和配对密度波序的涡流，还能在电荷密度波中引发拓扑缺陷，进而诱导实验观测到的在上临界场处电荷序的熔化现象。此项研究不仅揭示了磁场诱导的拓扑缺陷在UTe2中电荷密度波序参数熔化过程中的重要作用，还为表面上存在配对密度波序提供了有力的支持。
据悉，拓扑缺陷是有序相中的奇异点，它可以对相变产生深远的影响，并作为进入有序参数的窗口。拓扑缺陷的例子包括电荷密度波中的位错和超导体或配对密度波中的涡旋，后者是具有有限动量的库珀对的凝聚。
附：英文原文
Title: Melting of the charge density wave by generation of pairs of topological defects in UTe2
Author: Aishwarya, Anuva, May-Mann, Julian, Almoalem, Avior, Ran, Sheng, Saha, Shanta R., Paglione, Johnpierre, Butch, Nicholas P., Fradkin, Eduardo, Madhavan, Vidya
Issue&Volume: 2024-03-20
Abstract: Topological defects are singularities in an ordered phase that can have a profound effect on phase transitions and serve as a window into the order parameter. Examples of topological defects include dislocations in charge density waves and vortices in a superconductor or pair density wave, where the latter is a condensate of Cooper pairs with finite momentum. Here we demonstrate the role of topological defects in the magnetic-field-induced disappearance of a charge density wave in the heavy-fermion superconductor UTe2. We reveal pairs of topological defects of the charge density wave with positive and negative phase winding. The pairs are directly correlated with zeros in the charge density wave amplitude and increase in number with increasing magnetic field. A magnetic field generates vortices of the superconducting and pair density wave orders that can create topological defects in the charge density wave and induce the experimentally observed melting of this charge order at the upper critical field. Our work reveals the important role of magnetic-field-generated topological defects in the melting of the charge density wave order parameter in UTe2 and provides support for the existence of a pair density wave order on the surface.
DOI: 10.1038/s41567-024-02429-9
Source: https://www.nature.com/articles/s41567-024-02429-9