Non-Ohmic conduction in exfoliated La0.7Ca0.3MnO3 thin films

Abstract

We present a strong non-Ohmic transport characteristic of the exfoliated La0.7Ca0.3MnO3 thin film obtained by growing a water-soluble sacrificial layer of Sr3Al2O6 between the SrTiO3 substrate and the La0.7Ca0.3MnO3 film. The non-Ohmic conduction manifests itself as a significant amount of electroresistance over a wide range of temperatures. The resistance shows a plateaulike feature at low temperatures, and the electroresistance reaches ∼50 000% at 10 K for input currents varying from 1024 nA to 125 pA. The structural characterization of the exfoliated film reveals the existence of antiphase boundaries, the tunneling through which appears to cause the non-Ohmic feature. Our results provide an avenue into colossal tunneling electroresistance mediated by crystallographic defects.

Poling Sequence-Dependent Tunneling Electroresistance in HfO2-Based Ferroelectric Tunnel Junctions

“…To further quantitatively explain above poling sequence-dependent I–V characteristics of the HZO films, we first averaged the OFF-state currents measured on each pad (Figure a,b) as shown in Figure a. Then the I–V curves were fitted with WKB approximation, assuming direct tunneling across trapezoidal electronic profile. The tunneling current density J through a barrier at low voltage range is given by J ≅ 4 e m 9 π 2 h 3 exp { α false( V false) true[ true( φ 2 − e V 2 true) 3 / 2 − true( φ 1 + e V 2 true) 3 / 2 true] } α 2 ( V ) [ ( φ 2 − e V 2 ) 1 / 2 − ( φ 1 + e V 2 ) 1 / 2 ] × sinh { 3 2 α false( V false) true[ …”

“…To further quantitatively explain above poling sequencedependent I−V characteristics of the HZO films, we first averaged the OFF-state currents measured on each pad (Figure 2a,b) as shown in Figure 4a. Then the I−V curves were fitted with WKB approximation, 28 assuming direct tunneling across trapezoidal electronic profile. The tunneling current density J through a barrier at low voltage range is given by…”

“…To further quantitatively explain above poling sequence-dependent I–V characteristics of the HZO films, we first averaged the OFF-state currents measured on each pad (Figure a,b) as shown in Figure a. Then the I–V curves were fitted with WKB approximation, assuming direct tunneling across trapezoidal electronic profile. The tunneling current density J through a barrier at low voltage range is given by where α­( V ) = [4 d (2 m ) 1/2 ]/[3 h (φ 1 + eV – φ 2 )], e is charge of electron, h is the Planck’s constant, and m is mass of electron, which is supposed to be 0.1 m 0 for HZO ( m 0 = the elementary electron mass). , Figure a shows the fitted OFF-state I–V curves and Figure b shows the schematic electronic band diagrams of the junctions with different poling sequence.…”