We report an angle-resolved photoemission spectroscopy study of the iron-based superconductor family, ${\mathrm{Ba}}_{1-x}{\mathrm{Na}}_x{\mathrm{Fe}}_2{\mathrm{As}}_2$. This system harbors the recently discovered double-$Q$ magnetic order appearing in a reentrant $C_4$ phase deep within the underdoped regime of the phase diagram that is otherwise dominated by the coupled nematic phase and collinear antiferromagnetic order. From a detailed temperature-dependence study, we identify the electronic response to the nematic phase in an orbital-dependent band shift that strictly follows the rotational symmetry of the lattice and disappears when the system restores $C_4$ symmetry in the low temperature phase. In addition, we report the observation of a distinct electronic reconstruction that cannot be explained by the known electronic orders in the system.

中文翻译：

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Ba1-xNaxFe2As2中紧急阶跃的光谱证据

我们报告了铁基超导体系列的角度分辨光发射光谱研究， ${巴}_{\mathrm{1个}-X}{娜}_X{铁}_{\mathrm{2个}}{\mathrm{作为}}_{\mathrm{2个}}$。该系统包含最近发现的双$问$ 折返中出现的磁性顺序 $C_4$在相图的未掺杂范围内的深相，否则将由耦合向列相和共线反铁磁阶控制。通过详细的温度依赖性研究，我们确定了与轨道有关的能带移动中向列相的电子响应，该带能严格遵循晶格的旋转对称性，并在系统恢复时消失$C_4$低温阶段的对称性。此外，我们报告观察到独特的电子重构，而该重构无法由系统中的已知电子订单进行解释。