Minimal electronic models for superconducting BiS2layers

“Checkerboard Stripe” Electronic State on Cleaved Surface of NdO0.7F0.3BiS2 Probed by Scanning Tunneling Microscopy

“…Recent theoretical calculations have suggested that a quasi-one-dimensional character of the band dispersion provides a good Fermi surface nesting [28][29][30][31][32] . Some of them have proposed that an unstable phonon at q = (q, q, 0) corresponding to the Fermi surface nesting vector causes a CDW instability 29,30 .…”

“…Some of them have proposed that an unstable phonon at q = (q, q, 0) corresponding to the Fermi surface nesting vector causes a CDW instability 29,30 . How the SC is related to this Fermi surface nesting has been argued vigorously [28][29][30][31][32][33][34][35] . Meanwhile, the symmetry of the superconducting gap has also been investigated theoretically and experimentally.…”

Electron-phonon superconductivity near charge-density-wave instability in LaO0.5F0.5BiS2Wan1, Ding2, Savrasov3 et al. 2013Phys. Rev. B159182272View full textAdd to dashboardCite

“…Here, the basic structural unit is the BiS 2 layer which is similar to the Cu-O planes in Cu-based superconductors[1] and the Fe-A (A=P, As, Se, Te) planes in iron pnictides [5]. A chance to explore superconductivity and increase T c in these new compounds has already resulted in a lot of work that appeared shortly after the discovery [1,7,[9][10][11][12][13][14][15][16]. Hall effect measurements reveal multiband features and suggest the superconducting pairing occurs in one-dimensional chains [10].…”

Observation of Supermodulation in LaO0.5F0.5BiSe2 by Scanning Tunneling Microscopy and Spectroscopy

“…In some theoretical calculations, possible CDW that is caused by Peierls mechanism has been proposed. From these theoretical calculations in LaO 1-x F x BiSe 2 , following features are expected.(i) The instability against CDW formation is expected to develop alongdirection in the k space [44].(ii) This instability of CDW is enhanced at the F concentration of 0.5, where Fermi surfaces connect [34][35][36][37].(iii) A period of the predicted CDW is expected to be √2 times of the lattice constant a 0, which is corresponding to the nesting vector along direction.The observed supermodulation is consistent with features (i) and (ii). On the other hand, the observed period of about 5 times of the lattice constant a 0 is inconsistent with (iii).…”

“…This higher T c remains at ambient pressure after as-grown polycrystalline samples are annealed under high pressure. These high-pressure effects indicate that the crystal structure of these materials is rather unstable against the external perturbations.Theoretical calculations also predicted electronic and structural instability against the formation of charge density wave (CDW) [34][35][36][37][38]. A calculation of band structures predicted due to nesting at the F concentration of x=0.5, where the Fermi surface connects at around (/2, /2) in the k space [34,35].…”