论文标题
$ \ mathrm {ba} _ {1-x} \ Mathrm {k} _ {x} \ Mathrm {fe} _ {2} _ {2} \ Mathrm {as} _ {2}
Interplay of stripe and double-Q magnetism with superconductivity in $\mathrm{Ba}_{1-x}\mathrm{K}_{x}\mathrm{Fe}_{2}\mathrm{As}_{2}$ under the influence of magnetic fields
论文作者
论文摘要
At $x\approx0.25$ $\mathrm{Ba}_{1-x}\mathrm{K}_{x}\mathrm{Fe}_{2}\mathrm{As}_{2}$ undergoes a novel first-order transition from a four-fold symmetric double-Q magnetic phase to a two-fold symmetric single-Q阶段，被认为与超导性发作同时发生（Böhmer等，Nat。Comm。6，7911（2015））。在这里，通过应用最多10T的磁场，我们使用高分辨率热扩张和热容量测量的组合，更详细地研究了超导性与这种磁结构过渡的相互作用。我们发现，磁场比超导过渡更强烈地抑制单Q骨相位相位的重新进入，从而导致零场一阶跃迁的分裂。与平面场和尺度相比，正面外部的抑制速率比具有超导状态的各向异性的面积和尺度更强。这些效果在现象学金茨堡 - 兰道模型中被捕获，强烈表明抑制重入原骨单Q相的抑制主要与田间诱导的超导顺序的弱化有关。然而，该模型未捕获的是平面外磁场的正交畸变的大大减少，这值得进一步的理论关注。
At $x\approx0.25$ $\mathrm{Ba}_{1-x}\mathrm{K}_{x}\mathrm{Fe}_{2}\mathrm{As}_{2}$ undergoes a novel first-order transition from a four-fold symmetric double-Q magnetic phase to a two-fold symmetric single-Q phase, which was argued to occur simultaneously with the onset of superconductivity (Böhmer et al., Nat. Comm. 6, 7911 (2015)). Here, by applying magnetic fields up to 10T, we investigate in more detail the interplay of superconductivity with this magneto-structural transition using a combination of high-resolution thermal-expansion and heat-capacity measurements. We find that a magnetic field suppresses the reentrance of the single-Q orthorhombic phase more strongly than the superconducting transition, resulting in a splitting of the zero-field first-order transition. The suppression rate of the orthorhombic reentrance transition is stronger for out-of-plane than for in-plane fields and scales with the anisotropy of the superconducting state. These effects are captured within a phenomenological Ginzburg-Landau model, strongly suggesting that the suppression of the reentrant orthorhombic single-Q phase is primarily linked to the field-induced weakening of the superconducting order. Not captured by this model is however a strong reduction of the orthorhombic distortion for out-of-plane fields, which deserves further theoretical attention.
