Fig. 1: Observation of bosonic mode in CsV3Sb5.
From: Evidence of a distinct collective mode in Kagome superconductors
a Phase diagram of CsV3-xTaxSb5. The superconducting (SC) transition temperature increases while the charge density wave (CDW) transition temperature decreases with increasing \(x\). The CDW is undetectable when \(x\) > 0.30. The transition temperatures of SC and CDW are obtained from transport measurement. The inset of (a) shows the crystal structure of CsV3Sb5. b The Fourier transform of the tunneling conductance dI/dV map taken at –2mV on a typical as-cleaved Sb surface of CsV3Sb5, showing the 4a0 CDW, 2a0\(\times\)2a0 CDW, 4a0/3\(\times\)4a0/3 CDW and 4a0/3\(\times\)4a0/3 pair density wave (PDW), and intriguing quasi-particle interference patterns, respectively. The a0 in (b) is the lattice constant. The Q1q-4a0, (Q3q-4a0/3) and QBragg in (b) are the wave vectors of 4a0 CDW, 4a0/3 CDW/PDW, and Bragg peaks, which are indicated by the colored circles. c A series of dI/dV spectra (lower panel) obtained along the line-cut (black dotted line) on the topography in the upper panel, showing two SC gaps accompanied by a pair of peak-dip-hump features just outside the SC gaps, indicative of a bosonic mode. d Same as in (c) but over a line-cut in a different spatial region (upper panel), where the dI/dV spectra (lower panel) are dominated by the spectral line-shape of a smaller gap in a more subtle two-gap structure. The peak-dip-hump features outside of the SC gaps are also clearly visible indicating the presence of a bosonic mode. For (c, d), the scanning tunneling microscope (STM) scanning parameters are bias setup (Vs) = −600 mV, current setup (It) = 400 pA and Vs = –20 mV, It = 1 nA, respectively, and the scanning tunneling spectroscopy (STS) parameters are the same: Vs = –2.0 mV, It = 1 nA, and lockin modulation amplitude (Vmod) = 0.05 mV.
