The magnetic properties of iron-based superconductors $A$Fe${}_2$As${}_2$ ($A=$K, Cs, and Rb), which are characterized by the V-shaped dependence of the critical temperature ($T_{\rm c}$) on pressure ($P$) were studied by means of the muon spin rotation/relaxation technique. In all three systems studied the magnetism was found to appear for pressures slightly below the critical one ($P_{\rm c}$), {} at pressure where $T_{\rm c}(P)$ changes the slope. Rather than competing, magnetism and superconductivity in $A$Fe${}_2$As${}_2$ are coexisting at $P\gtrsim P_{\rm c}$ pressure region. Our results support the scenario of a transition from one pairing state to another, with different symmetries on either side of $P_{\rm c}$.

中文翻译：

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铁基超导体AFe2As2（A = K，Cs，Rb）中的压力感应磁性

铁基超导体的磁性 $\mathrm{一种}$铁${}_2$如${}_2$ （$\mathrm{一种}=$K，Cs和Rb），其特征在于临界温度（$ T _ {\ rm c} $）对压力（$P$）是通过μ自旋旋转/松弛技术进行研究的。在所研究的所有三个系统中，发现在压力稍微低于临界值（$ P _ {\ rm c} $）{}的情况下，在$ T _ {\ rm c}（P）$改变斜率的压力下才会出现磁性。与其竞争，不如说是磁场和超导$\mathrm{一种}$铁${}_2$如${}_2$在$ P \ gtrsim P _ {\ rm c} $压力区域共存。我们的结果支持从一种配对状态过渡到另一种配对状态的场景，在$ P _ {\ rm c} $的任一侧具有不同的对称性。