Gap symmetry and structure are crucial issues in understanding the superconducting mechanism of unconventional superconductors. Here, we report an in-depth investigation on the out-of-plane lower critical field \(H_{c1}^c\) of fluorine-based 1111 system superconductor CaFe_0.88Co_0.12AsF with T_c = 21 K. A pronounced two-gap feature is revealed by the kink in the temperature-dependent \(H_{c1}^c(T)\) curve. The magnitudes of the two gaps are determined to be Δ₁ = 0.86 meV and Δ₂ = 4.48 meV, which account for 74% and 26% of the total superfluid density, respectively. Our results suggest that the local antiferromagnetic exchange pairing picture is favored compared to the Fermi surface nesting scenario.

间隙对称性和结构是理解非常规超导体超导机理的关键问题。在此，我们报告了对基于氟的1111系统超导体CaFe _0.88 Co _0.12 AsF（T _c  = 21 K ）的面外下临界场\（H_ {c1} ^ c \）的深入研究。在取决于温度的\（H_ {c1} ^ c（T）\）曲线中的纽结处揭示了两个间隙特征。两个间隙的大小被确定为Δ ₁  = 0.86兆电子伏和Δ ₂ = 4.48 meV，分别占总超流体密度的74％和26％。我们的结果表明，与费米表面嵌套方案相比，局部反铁磁交换配对图片更为有利。