Superconductivity in an Orbital‐Reoriented SnAs Square Lattice: A Case Study of Li_0.6Sn₂As₂ and NaSnAs

Abstract

Searching for functional square lattices in layered superconductor systems offers an explicit clue to modify the electron behavior and find exotic properties. The trigonal SnAs3 structural units in SnAs‐based systems are relatively conformable to distortion, which provides the possibility to achieve structurally topological transformation and higher superconducting transition temperatures. In the present work, the functional As square lattice was realized and activated in Li0.6Sn2As2 and NaSnAs through a topotactic structural transformation of trigonal SnAs3 to square SnAs4 under pressure, resulting in a record‐high Tc among all synthesized SnAs‐based compounds. Meanwhile, the conductive channel transfers from the out‐of‐plane pz orbital to the in‐plane px+py orbitals, facilitating electron hopping within the square 2D lattice and boosting the superconductivity. The reorientation of p‐orbital following a directed local structure transformation provides an effective strategy to modify layered superconducting systems.

Two-Dimensional Pb Square Nets from Bulk (RO)nPb (R = Rare Earth Metals, n = 1,2)

“…The compounds synthesized in this work are summarized in Table , representing only a small portion of the potential candidates of monolayers sandwiched between insulating layers. At the outset, it is worth noting that the synthesis of other two-dimensional monoelements, such as Si, Ge, and Sn, as well as other p -block elements or even d -block metals, is possible using the method described here, − ,− and has the potential to yield a wide range of new material categories with unique properties. By carefully controlling the charge donation from the [La 2 O 2 ] 2+ layer through the substitution of divalent alkali-earth elements, it is possible to precisely adjust the buckling height and thereby alter the transport properties of the underlying 2D-Pb square net.…”

Intrinsic Coherence Length Anisotropy in Nickelates and Some Iron-Based Superconductors

“…These rare but high-quality experimental reports provide additional evidence for the need to define the by at least the criterion, which is the most accurate experimental value for the superconducting state collapse/emergence if only resistive measurements have been performed for the given sample. This definition has been implemented, but, again, in very rare studies [ 82 , 87 , 91 , 92 , 93 ] in comparison with the majority of studies, where was defined by the criterion (see, for instance, [ 94 , 95 ]).…”