Anomalous Upper Critical Field in CeCoIn5/YbCoIn5 Superlattices with a Rashba-Type Heavy Fermion Interface
Anomalous Upper Critical Field in CeCoIn5/YbCoIn5 Superlattices with a Rashba-Type Heavy Fermion Interface
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DOI：
10.1103/physrevlett.109.157006
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发表时间：
2012-10-12
影响因子：
8.6
通讯作者：
Matsuda, Y.
中科院分区：
文献类型：
--
作者：
Goh, S. K.;Mizukami, Y.;Matsuda, Y.
我们报道了外延超晶格CeCoIn5(N)/YbCoIn5(5)的上临界场(H-c2)的极不寻常的角变化，该外延超晶格分别由n层和具有强Pauli效应的5单元厚的重费米子超导体CeCoIn5和正常金属YbCoIn5组成。对于n=3的超晶格，H-c2(Theta)随场角theta的变化而平稳变化。然而，在接近超导转变温度时，H-c2(Theta)在平行场(theta=0度)附近出现尖点。对于n=4和5的超晶格，这种尖点行为消失了。这种突然消失表明在n=3超晶格中轨道失配效应相对占优势，这可能是由于局域反转对称破缺系统中泡利效应被抑制所致。考虑到H-c2(Theta)与温度的关系，我们的结果表明，某些奇异的超导态，包括螺旋超导态，可能在强磁场下实现。
We report a highly unusual angular variation of the upper critical field (H-c2) in epitaxial superlattices CeCoIn5(n)/YbCoIn5(5), formed by alternating layers of n and a 5 unit-cell thick heavy-fermion superconductor CeCoIn5 with a strong Pauli effect and normal metal YbCoIn5, respectively. For the n = 3 superlattice, H-c2(theta) changes smoothly as a function of the field angle theta. However, close to the superconducting transition temperature, H-c2(theta) exhibits a cusp near the parallel field (theta = 0 degrees). This cusp behavior disappears for n = 4 and 5 superlattices. This sudden disappearance suggests the relative dominance of the orbital depairing effect in the n = 3 superlattice, which may be due to the suppression of the Pauli effect in a system with local inversion symmetry breaking. Taking into account the temperature dependence of H-c2(theta) as well, our results suggest that some exotic superconducting states, including a helical superconducting state, might be realized at high magnetic fields.