Negative Differential Resistance Induced by Mn Substitution at SrRuO3/Nb:SrTiO3 Schottky Interfaces

TL;DR

This study demonstrates how Mn substitution in SrRuO3 modifies Schottky interface properties, inducing negative differential resistance and resonant states, revealing a new way to control interface states via impurity sensitivity.

Contribution

It introduces a novel method of tuning interface states in Schottky junctions through Mn doping in SrRuO3, affecting electronic properties and inducing negative differential resistance.

Findings

Mn substitution induces a metal-insulator transition in SrRuO3.

Negative differential resistance observed at low temperatures.

Resonant states originate from interface SrRuO3 layer.

Abstract

We observed a strong modulation in the current-voltage characteristics of SrRuO$_3$/Nb:SrTiO$_3$ Schottky junctions by Mn substitution in SrRuO$_3$, which induces a metal-insulator transition in bulk. The temperature dependence of the junction ideality factor indicates an increased spatial inhomogeneity of the interface potential with substitution. Furthermore, negative differential resistance was observed at low temperatures, indicating the formation of a resonant state by Mn substitution. By spatially varying the position of the Mn dopants across the interface with single unit cell control, we can isolate the origin of this resonant state to the interface SrRuO$_3$ layer. These results demonstrate a conceptually different approach to controlling interface states by utilizing the highly sensitive response of conducting perovskites to impurities.