Fig. 3: Fingerprints of Mott transition and ‘6K anomaly’ in transport gap.
From: Chasing the spin gap through the phase diagram of a frustrated Mott insulator
The transport gap \(d\ln R/d\ 1/T\) determined from the strain-dependent resistance (Fig. 2c) is compared to ambient pressure (black dashed line from ref. 28). While biaxial compression εbiaxial < 0 causes a reduction of the gap size, equivalent to a vertical shift of the p = 0 data by −130 K (gray dotted), the gap increases upon tensile strain εc > 0, consistent with the bandwidth-tuning in Fig. 2b. The Mott MIT is evident from the sign change at TBR. Upon further cooling in the metallic state, \(d\ln R/d\ 1/T\to 0\) as the residual resistivity is approached, followed by a sharp drop when SC sets in. Notably, the fully insulating curves exhibit a local maximum around T⋆ = 6 K associated with the VBS transition.
