Superconductivity at 5 K in quasi-one-dimensional Cr-based KCr3As3 single crystals

Abstract

Recently a new family of Cr-based A 2 Cr 3 As 3 (A = K, Rb, Cs) superconductors were reported, which own a rare quasi-one-dimensional (Q1D) crystal structure with infinite (Cr 3 As 3 ) 2chains and exhibit intriguing superconducting characteristics possibly derived from spin-triplet electron pairing. The crystal structure of A 2 Cr 3 As 3 is actually a slight variation of the hexagonal TlFe 3 Te 3 prototype although they have different lattice symmetry. Here we report superconductivity in a 133-type KCr 3 As 3 compound that belongs to the latter structure. The single crystals of KCr 3 As 3 were prepared by the deintercalation of K ions from K 2 Cr 3 As 3 crystals which were grown from a high-temperature solution growth method, and it owns a centrosymmetric lattice in contrast to the non-centrosymmetric K 2 Cr 3 As 3 .After annealing at a moderate temperature, the KCr 3 As 3 crystals show bulk superconductivity at 5 K revealed by electrical resistivity, magnetic susceptibility and heat capacity measurements. The discovery of this KCr 3 As 3 superconductor provides a different structural instance to study the exotic superconductivity in these Q1D Cr-based superconductors.

Lifshitz transition enhanced triplet $p_z$-wave superconductivity in hydrogen doped KCr$_3$As$_3$

“…Slightly after the synthesization of the A 2 Cr 3 As 3 (233) family, its air-insensitive cousin family A 1 Cr 3 As 3 (133) were obtained by removing half of the A + ions through an ethanol bath at room temperature [29][30][31][32]. The 133 family shares similar quasi-1D crystalline structure and low-energy degrees of freedom with the 233 family [33].…”

“…Initially, there exists obvious conflict on the ground state property of the 133 family. While the works reported in Ref [29,30,34] suggest the 133 family to be nonsuperconducting with a spin-glass ground state, definite evidence for superconductivity (SC) has been identified in the work reported in Ref [31,32]. This conflict was finally reconciled by the revelation using neutron and Xray diffraction [35] that the hydrogen atoms intercalated in the material play the crucial role for the appearance of SC [35][36][37].…”

Exploring Topological Superconductivity in Topological Materials

“…K 2 Cr 3 As 3 was the first synthesized member, with = 6.1 K, and then, Rb 2 Cr 3 As 3 ( = 4.8 K) and Cs 2 Cr 3 As 3 ( = 2.2 K) were discovered. Recently, Na 2 Cr 3 As 3 , with ≈ 8.6 K, was also successfully synthesized by an ion‐exchange synthesis method . appears to decrease with increasing radius of the A ions in the A 2 Cr 3 As 3 series ( A = Na, K, Rb, Cs).…”

Topological $p_z$-wave nodal-line superconductivity with flat surface bands in the AH$_{x}$Cr${_3}$As${_3}$ (A=Na, K, Rb, Cs) superconductors

“…There are two Q1D Crbased superconductors families, i.e. the A 2 Cr 3 As 3 (abbreviated as the 233) family (A=Na, K, Rb, Cs) and the ACr 3 As 3 (abbreviated as the 133) family [30][31][32][33][34][35][36][37][38][39], with both sharing the same Q1D alkalinecations-separated [(Cr 3 As 3 ) 2− ] ∞ double-walled subnanotubes (DWSN) structure. The 233 family were synthesized earlier, and have shown unconventional pairing nature [2][3][4][5]7,[20][21][22][23]25,40] with possible triplet pairing symmetry [2, 18, 20-22, 25, 40, 41].…”

“…The 233 family were synthesized earlier, and have shown unconventional pairing nature [2][3][4][5]7,[20][21][22][23]25,40] with possible triplet pairing symmetry [2, 18, 20-22, 25, 40, 41]. The 133 family were synthesized slightly later, obtained by deintercalating half of the alkali metal atoms with ethanol [33][34][35][36]. The primitive ACr 3 As 3 have a spin glass ground state [33,34,39], which is consistent with the relaxation behavior of density functional theory (DFT) calculations [37][38][39]42] and the muon spin-rotation (µSR) experiments [5].…”