SCIENTIFIC HIGHLIGHTS RL3, Articles

Resistive switching in semimetallic thin films

The study of different thickness SrIO3 thin films shows different behaviors, from insulating to semimetallic, in resistive switching memory devices

Iridates are of strong interest because large spin-orbit coupling (SOC) is expected in these materials, thus the interplay between magnetic and electronic properties will be strongly reinforced opening the access to new magneto-electronic devices.

In the search for a new generation of faster and more energy efficient electronic devices, the use of reversible resistive switching (RS) phenomena has been proposed as a very appealing solution for the development of non-volatile memory devices. Here we address the analysis of resistive switching processes in SrIrO3 thin films by means of local Intensity-Voltage (I-V) curve measurements and current mapping, by using conductive atomic force microscopy (C-AFM).

While SrIrO3 exhibits semimetallic character, in thin films, an Anderson-type metal-insulator transition (MIT) triggered by disorder and spatial localization due to film thickness reduction is observed, and their influence on the resistive switching behaviour is analysed. For thin enough films (below ~3nm) samples are insulating with hysteretic I-V curves indicative of reversible resistive switching behaviour between two states of clearly different resistance at room temperature. A sharp transition into a low resistance state (LRS), i.e an abrupt increase of the current intensity, is detected above a well-defined threshold voltage indicative of localization of charge carriers. On the other hand, thicker samples exhibit a semimetallic character and I-V curves show progressive changes of the local resistance without a clearly defined threshold voltage, thus evidencing the absence of a MI transition with a well-defined resistance jump between the different resistance states.

Resistive Switching in Semimetallic SrIrO3 Thin Films
Víctor Fuentes, Borislav Vasić, Zorica Konstantinović, Benjamín Martínez, Lluís Balcells, Alberto Pomar
ACS Appl. Electron. Mater. 1, 1981−1988, 2019
DOI: 10.1021/acsaelm.9b00519

Figure: Left: Disorder and spatial localization due to thickness reduction allow generating a metal-insulator transition in semimetallic SrIrO3 thin films. Below about 3nm films are insulating with hysteretic I-V curves indicative of resistive switching behavior at room temperature. Right: Current maps (a and c) allow demonstrating the writing/erasing processes required for the implementation of Re-RAMs. Corresponding topography images (b, d).

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