Achieving large and nonvolatile tunable magnetoresistance in organic spin valves using electronic phase separated manganites

Wenting Yang,Wenbin Wang,Yinyan Zhu,Qiang Li,Hao Liu,Yu Bai,Jian Shen,Qian Shi,Hanxuan Lin,Dali Sun,Tian Miao,Lina Deng,Yang Yu,X.-G Zhang,Lifeng Yin,Peng Cai

doi:10.1038/s41467-019-11827-0

Abstract

Tailoring molecular spinterface between novel magnetic materials and organic semiconductors offers promise to achieve high spin injection efficiency. Yet it has been challenging to achieve simultaneously a high and nonvolatile control of magnetoresistance effect in organic spintronic devices. To date, the largest magnetoresistance (~300% at T = 10 K) has been reached in tris-(8-hydroxyquinoline) aluminum (Alq3)-based organic spin valves (OSVs) using La0.67Sr0.33MnO3 as a magnetic electrode. Here we demonstrate that one type of perovskite manganites, i.e., a (La2/3Pr1/3)5/8Ca3/8MnO3 thin film with pronounced electronic phase separation (EPS), can be used in Alq3-based OSVs to achieve a large magnetoresistance (MR) up to 440% at T = 10 K and a typical electrical Hanle effect as the Hallmark of the spin injection. The contactless magnetic field-controlled EPS enables us to achieve a nonvolatile tunable MR response persisting up to 120 K. Our study suggests a new route to design high performance multifunctional OSV devices using electronic phase separated manganites.

Highlights

Tailoring molecular spinterface between novel magnetic materials and organic semiconductors offers promise to achieve high spin injection efficiency
We show that magnetic field induced modulation of the ferromagnetic metallic (FMM) and charge ordered insulating (COI) phase in the LPCMO thin film leads to a tunable MR effect up to 120 K above which the phase separation disappears
We demonstrate that a large MR effect of ~440% can be created in Alq[3] molecule-based spin valve device using a LPCMO thin film with pronounced electronic phase separation (EPS) as the bottom electrode

Summary

Introduction

Tailoring molecular spinterface between novel magnetic materials and organic semiconductors offers promise to achieve high spin injection efficiency. We demonstrate that one type of perovskite manganites, i.e., a (La2/3Pr1/3)5/8Ca3/8MnO3 thin film with pronounced electronic phase separation (EPS), can be used in Alq3-based OSVs to achieve a large magnetoresistance (MR) up to 440% at T = 10 K and a typical electrical Hanle effect as the Hallmark of the spin injection. In spite of a large number of members in manganites family, La0.67Sr0.33MnO3 (LSMO) has been almost the only material used in OSVs10,14,22,29,30 This is probably because most other manganite films have pronounced electronic phase separation (EPS) featured by coexistence of ferromagnetic metallic (FMM) and non-ferromagnetic insulating phases, which would presumably lower the spin polarization and are considered as non-favorable materials for spin injection. The LPCMO thin film is suitable for an efficient spin injection owing to its half-metallic nature that would significantly suppress the conductivity mismatch between organic molecules and oxide surface

Methods

Results

Conclusion