Effect of substrate temperature on the spin transport property in C60-based spin valve devices

TL;DR

This study investigates how substrate temperature influences the magnetoresistance in C60-based spin valve devices, revealing higher temperatures enhance MR due to increased tunneling facilitated by surface irregularities.

Contribution

It demonstrates that increasing substrate temperature significantly improves MR in C60 spin valves by inducing surface pits that promote spin-polarized tunneling.

Findings

Higher substrate temperatures lead to increased MR ratios.

Surface pits from higher temperatures facilitate spin tunneling.

Maximum MR of 28.5% achieved at elevated substrate temperature.

Abstract

We report the effect of the substrate temperature on the magnetoresistance (MR) of the C60-based spin valve (SV) devices with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/C60/cobalt (Co). The C60 interlayer deposited at different substrate temperatures resulted in four types of devices. We observed all types of devices showed a monotonic increase in MR ratio with the substrate temperature. And more interesting, an especially large MR (28.5%) were obtained in the device fabricated at higher substrate temperature, while for the other types of devices, the MR magnitudes were just about a few percent. Based on the I-V measurements, as well as SEM and AFM characteristics, we have obtained that the higher substrate temperature can cause many pits and hollows in the organic film, and these pits will increase the tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other.