Observation of superconductivity and its enhancement at the charge density wave critical point in LaAgSb2

Abstract

We discover superconductivity (SC) in LaAgSb 2 at ambient pressure and its close correlation with a charge density wave (CDW) under pressure. The superconducting transition temperature (T c ) exhibits a sharp peak at a CDW critical pressure of 3.2 GPa. We demonstrate that the carriers inhabiting the Sb-square net are crucial not only in the formation of CDW but also in SC for their relatively strong electron-phonon coupling (EPC). Furthermore, theoretical EPC strength in pristine LaAgSb 2 cannot explain the observed peak with T c ∼ 1 K, which indicates that an additional mechanism reinforces SC only around the CDW critical pressure.

Superconductivity and Charge-Density-Wave-Like Transition in Th2Cu4As5

“…42 On the other hand, for LaCuSb 2 and LaAgSb 2 , which exhibit superconductivity with lower T c than that of Th 2 Cu 4 As 5 , the contribution of d-orbital to the conduction band is also less pronounced. 20,42,43 In short, the above-mentioned research collectively converges on an empirical rule: the transition temperatures of CDW and superconductivity are positively correlated with the contribution of the p-orbital and d-orbital to N(E F ), respectively. Therefore, it is reasonable to conjecture that in Th 2 Cu 4 As 5 , the superconductivity may be associated with the Cu 4 As 3 slabs, while the CDW-like phase transition could be ascribed to the As(2) square sheets.…”

“…Intriguingly, analogous As/Sb planes are prevalent in 112-type LnTPn 2 compounds, where Ln represents lanthanides, T denotes Cu, Ag, and Au, and Pn stands for As or Sb. ,− Some of these compounds, such as LaAgSb 2 and LaAuSb 2 , exhibit CDW states with even higher transition temperatures than those of Th 2 Cu 4 As 5 . ,, Notably, the primary contribution to N ( E F ) in the 112-type pnictides stems from the p orbital . On the other hand, for LaCuSb 2 and LaAgSb 2 , which exhibit superconductivity with lower T c than that of Th 2 Cu 4 As 5 , the contribution of d-orbital to the conduction band is also less pronounced. ,, In short, the above-mentioned research collectively converges on an empirical rule: the transition temperatures of CDW and superconductivity are positively correlated with the contribution of the p-orbital and d-orbital to N ( E F ), respectively. Therefore, it is reasonable to conjecture that in Th 2 Cu 4 As 5 , the superconductivity may be associated with the Cu 4 As 3 slabs, while the CDW-like phase transition could be ascribed to the As(2) square sheets.…”

Detection of Nontrivial Topology Driven by Charge Density Wave in a Semi‐Dirac Metal

“…These observations are consistent with the growing understanding that while one may have regions of the Fermi surface parallel to each other, usually other effects take over and the direction of the CDW modulation has little or no connection with the nesting vector. NMR experiments reveal the emergence of only two distinct La species which seems unusual [ 39 ] despite the long wavelength associated with the CDW at 211 K. More importantly, the recent observation of coexisting CDW and superconductivity <300 mK, [ 40 ] further suggests the presence of a strong electron–phonon coupling as has been used to discuss the properties of the cuprates, [ 41 ] NbSe 2 , [ 42 ] and 2H‐TaSe 2 . [ 43 ]…”