论文标题
费用订单中断CSV $ _3 $ sb $ _5 $中的时间反转对称性
Charge order breaks time-reversal symmetry in CsV$_3$Sb$_5$
论文作者
论文摘要
最近发现的基于气泡的Kagome金属$ a $ v $ _ {3} $ sb $ _ {5} $（$ a $〜= 〜k，〜rb，〜cs）在低温和电荷密度波（CDW）下表现出超导性的超导性。该家族中电荷有序状态的一个突出特征是它破坏了时间反转对称性（TRSB），该对称性与频带结构的基本拓扑性质有关。在这项工作中，使用零场和高场振旋旋转/放松的强大组合来研究CSV $ _3 $ _3 $ sb $ _5 $的电荷订单的TRSB签名以及其各向异性特征。 By tracking the temperature evolution of the in-plane and out-of-plane components of the muon-spin polarization, an enhancement of the internal field width sensed by the muon-spin ensemble was observed below $T_{\rm TRSB}=T_{\rm CDW}\simeq95$~K.在$ T^\ ast \ ast \ simeq30 $ 〜k以下检测到了内部场宽度的进一步增加，并伴随着MUON站点从$ ab $平面更改本地场方向。值得注意的是，当沿着晶体学$ c-$轴施加8〜T的磁场时，这一两步特征变得很明显，因此表明在CDW过渡时具有场诱导的电子响应的增强。这些结果指向CSV $ _3 $ sb $ _5 $的TRSB，发起$ {\ simeq} 〜95 $ 〜k，随后是$ {\ simeq} 〜30 $ 〜k的增强的电子响应。在不同的电荷订购稳定性的框架内讨论了观察到的两步转变，根据密度功能理论的计算，能量的能量几乎是退化的。
The recently discovered vanadium-based kagome metals $A$V$_{3}$Sb$_{5}$ ($A$~=~K,~Rb,~Cs) exhibit superconductivity at low-temperatures and charge density wave (CDW) order at high-temperatures. A prominent feature of the charge ordered state in this family is that it breaks time-reversal symmetry (TRSB), which is connected to the underlying topological nature of the band structure. In this work, a powerful combination of zero-field and high-field muon-spin rotation/relaxation is used to study the signatures of TRSB of the charge order in CsV$_3$Sb$_5$, as well as its anisotropic character. By tracking the temperature evolution of the in-plane and out-of-plane components of the muon-spin polarization, an enhancement of the internal field width sensed by the muon-spin ensemble was observed below $T_{\rm TRSB}=T_{\rm CDW}\simeq95$~K. Additional increase of the internal field width, accompanied by a change of the local field direction at the muon site from the $ab$-plane to the $c$-axis, was detected below $T^\ast\simeq30$~K. Remarkably, this two-step feature becomes well pronounced when a magnetic field of 8~T is applied along the crystallographic $c-$axis, thus indicating a field-induced enhancement of the electronic response at the CDW transition. These results point to a TRSB in CsV$_3$Sb$_5$ by charge order with an onset of ${\simeq}~95$~K, followed by an enhanced electronic response below ${\simeq}~30$~K. The observed two-step transition is discussed within the framework of different charge-order instabilities, which, in accordance with density functional theory calculations, are nearly degenerate in energy.
