Unconventional superconductivity near frustrated orders in quasi-one-dimensional CrAs based systems

Even in the absence of a microscopic theory, a generalized recipe has emerged for unconventional superconductivity. In the common scenario, some ordered phase in a strongly-ish correlated material is suppressed giving rise to quantum fluctuations which can act as a possible pairing mechanism. The nature of these fluctuations – whether they are of the ordered phase, resultant of a quantum critical point or some more exotic pair density wave – is still hotly debated. Therefore, it is useful to find new unconventional superconductors which can provide further insight into the most relevant components of this recipe. The recently discovered family of A_xTM₃As₃ (A = Alkali, x = 1,2 and TM = Cr, Mo) superconductors provides such an opportunity in a system with a novel quasi-one-dimensional structure. In this presentation the latest results of joint ab initio and neutron scattering studies will be discussed which reveal a frustrated structural instability in K₂Cr₃As₃. Together with our previous reports of spin-fluctuations, this observation indicates a rich phase diagram for this system analogous to the traditional unconventional superconductors.