论文标题
在无限层镍nd $ _ {0.775} $ sr $ _ {0.225} $ nio $ _ {2} $
Isotropic Pauli-Limited Superconductivity in the Infinite Layer Nickelate Nd$_{0.775}$Sr$_{0.225}$NiO$_{2}$
论文作者
论文摘要
薄膜无限层中超导性的最近观察到$^{1-3} $提供了不同的角度来研究分层氧化物$^{4} $中的超导性。已经提出了广泛的候选模型$^{5-10} $，强调了单一或多轨电子结构，近托或Hund的耦合以及与丘比特的类比。显然，需要对超导状态进行进一步的实验表征，以便对镍镍产生充分的了解。在这里，我们使用MagnEtotransport测量值来探测ND $ _ {0.775} $ SR $ _ {0.225} $ nio $ $ _ {2} $中的超导对象。我们发现，尽管有分层的晶体结构，但在低温下，临界场是各向同性的。在磁场中，超导性是强限的，因此顺磁性效应在轨道去配对上占主导地位。潜在的各向同性反应是超导相干长度的实质各向异性，其面板内的时间是平面外的四倍。上临界场中突出的低温上流表明存在非常规的基态。
The recent observation of superconductivity in thin film infinite-layer nickelates$^{1-3}$ offers a different angle to investigate superconductivity in layered oxides$^{4}$. A wide range of candidate models have been proposed$^{5-10}$, emphasizing single- or multi-orbital electronic structure, Kondo or Hund's coupling, and analogies to cuprates. Clearly, further experimental characterization of the superconducting state is needed to develop a full understanding of the nickelates. Here we use magnetotransport measurements to probe the superconducting anisotropy in Nd$_{0.775}$Sr$_{0.225}$NiO$_{2}$. We find that the upper critical field is surprisingly isotropic at low temperatures despite the layered crystal structure. In a magnetic field the superconductivity is strongly Pauli-limited, such that the paramagnetic effect dominates over orbital de-pairing. Underlying this isotropic response is a substantial anisotropy in the superconducting coherence length, which is at least four times longer in-plane than out-of-plane. A prominent low-temperature upturn in the upper critical field indicates the presence of an unconventional ground state.
