Fig. 2
From: Enhanced flexoelectricity at reduced dimensions revealed by mechanically tunable quantum tunnelling
Flexoelectric control of electron tunnelling. a–c Schematics of the potential energy profiles across SrTiO3 (STO) with increasing flexoelectric polarisation (P; blue arrows). The additional electrostatic potential induced by P modifies the original barrier potential energy (black dotted line) to yield the total potential energy (green solid line). At the critical polarisation Pc, the tunnel barrier becomes triangular with φ1 = 0 and φ2 = φ0,2 + φ0,1∙(δPtIr/δSRO). d–f Measured tunnel current–voltage (I–V) curves across the nine unit cell-thick STO film for three representative ∂ut/∂x3 values. The red solid line in d indicates the fit to Equation (5). g The rectification ratios (RRs) |I+V/I–V| of the measured tunnel current as a function of ∂ut/∂x3. With increasing ∂ut/∂x3, the tunnelling I‒V curves become more asymmetric in regime (A) (yellow) below ∂ut/∂x3 = 1.56 × 107 m−1, but more symmetric in regime (B) (blue). h The simulated |I+V/I–V| at V = 0.2 V as a function of barrier-asymmetry, defined as φ2 – φ1. We set the initial barrier heights as φ1 = 1.3 eV and φ2 = 1.7 eV, and systematically decrease φ1 (or increased φ2) while fulfilling the condition (1.3 – φ1)/(φ2–1.7) = 8. Source data are provided as a Source Data file
