论文标题
NMR和NQR关于过渡金属砷超导体LARU2AS2，KCA2FE4AS4F2和A2CR3AS3的研究
NMR and NQR studies on transition-metal arsenide superconductors LaRu2As2, KCa2Fe4As4F2, and A2Cr3As3
论文作者
论文摘要
我们报告了75AS-核磁共振（NMR）和核四极共振（NQR）对过渡金属砷Laru2AS2，KCA2FE4AS4F2和A2CR3AS3进行的测量。在LARU2AS2的超导状态下，在TC以下的自旋晶格弛豫率-1/T1的温度依赖性中发现了一个希贝尔 - 较高的相干峰，这表明LARU2AS2是一个完整的间隙超质体。对于KCA2FE4AS4F2，在正常状态下观察到抗磁性自旋波动。我们进一步发现，各向异性速率RAF = TC1/TAB1很小，温度无关，这意味着低能自旋波动在自旋空间中是各向同性的。我们的结果表明，KCA2FE4AS4F2是具有化学计量成分的中等中等量超过的高温超导体。对于A2CR3AS3，我们通过第一原则方法计算电场梯度，并为75AS-NQR峰分配了两个晶体学上不同的位点，为进一步的NMR研究铺平了道路。
We report 75As-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements on transition-metal arsenides LaRu2As2, KCa2Fe4As4F2, and A2Cr3As3. In the superconducting state of LaRu2As2, a Hebel- Slichter coherence peak is found in the temperature dependence of the spin-lattice relaxation rate-1/T1 just below Tc, which indicates that LaRu2As2 is a full-gap superperconducor. For KCa2Fe4As4F2, antiferromagnetic spin fluctuations are observed in the normal state. We further find that the anisotropy rate RAF = Tc1/Tab1 is small and temperature independent, implying that the low energy spin fluctuations are isotropic in spin space. Our results indicate that KCa2Fe4As4F2 is a moderately overdoped iron-arsenide high-temperature superconductor with a stoichiometric composition. For A2Cr3As3, we calculate the electric field gradient by first-principle method and assign the 75As-NQR peaks with two crystallographically different As sites, paving the way for further NMR investigation.
