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.

拓扑缺陷是有序相中的奇点，它可以对相变产生深远的影响，并充当有序参数的窗口。拓扑缺陷的例子包括电荷密度波中的位错和超导体或对密度波中的涡流，其中后者是具有有限动量的库珀对的凝聚体。在这里，我们证明了重费米子超导体 UTe ₂中拓扑缺陷在磁场引起的电荷密度波消失中的作用。我们揭示了正负相绕组电荷密度波的成对拓扑缺陷。这些对与电荷密度波振幅的零点直接相关，并且数量随着磁场的增加而增加。磁场产生超导和对密度波序的涡旋，可以在电荷密度波中产生拓扑缺陷，并引起实验观察到的该电荷序在上临界场的熔化。我们的工作揭示了磁场产生的拓扑缺陷在UTe ₂中电荷密度波序参数熔化中的重要作用，并为表面上电子对密度波序的存在提供了支持。