Fig. 2
From: Visualizing heavy fermion confinement and Pauli-limited superconductivity in layered CeCoIn5
Atomic scale variation of the fermion mass. a–c Topographic images with color-coded dots indicating the spatial positions where the STM tunneling spectra were acquired (with corresponding colors in e–g; Vbias = −100 meV and Isetpoint = 1.7 nA). In a, b the spectra were obtained along lines parallel to the b-axis that are one lattice constant long (b = 4.6 Å). They display negligible spatial variation (e, f) and correspond to light (layer A) and heavy mass (layer B), respectively. c, g Tunneling spectra across a one lattice constant long (c = 7.5 Å) line parallel to the c-axis between two consecutive B layers showing alternating peak–dip structure and indicating that the observed electron mass varies with the position in the unit cell. The same smooth background is subtracted from all spectra and the curves are vertically shifted for clarity. d The spatial dependence of the modeled tunneling sensitivity ratio (t f /t c ), where t f and t c describes the sensitivity of tunneling into the heavy and light part of the excitations, respectively. Color scale shows the ratio from −0.54 to −0.3. h Calculated tunneling spectra along the c-axis
