Modification of the magnetic tunnel junction properties

TL;DR

This paper investigates the electro-physical properties of Fe/MgO/Fe magnetic tunnel junctions, focusing on fabrication conditions, interlayer diffusion, and the occurrence of negative differential resistance, with implications for MRAM and tunneling diode applications.

Contribution

It presents new insights into how fabrication conditions affect MTJ degradation and reveals the formation of excitons causing negative differential resistance in MgO layers.

Findings

Negative differential resistance observed in I-V characteristics.

Interlayer diffusion impacts MTJ degradation.

Exciton formation explains the negative differential resistance.

Abstract

We study the electro-physical properties of the Fe/MgO/Fe magnetic tunnel junctions (MTJ). Sample structures are fabricated on top of glass-ceramic substrates by e-beam evaporation in a relatively low vacuum (~10^-4 Torr). The influence of the first magnetic layer fabrication conditions on the degradation of the MTJ is explained by the interlayer diffusion. Various models of electro-physical processes in MTJ on polycrystalline substrates are discussed. The current-voltage (I-V) characteristics of the fabricated structures are found to exhibit the region with the negative differential resistance, similar to the one in tunneling diodes. We explain this phenomenon by the formation of excitons in the MgO layer modified by impurities. Obtained results will be useful in the development of MRAM devices containing MTJs and tunneling diodes.