Quenching of Spin Polarization Switching in Organic Multiferroic Tunnel Junctions by Ferroelectric “Ailing-Channel” in Organic Barrier

Shiheng Liang (1, 2) , Zhongwei Yu (1, 3) , Xavier Devaux (1) , Anthony Ferri (4) , Weichuan Huang (5) , Huaiwen Yang (1) , Rachel Desfeux (4) , Xiaoguang Li (5) , Sylvie Migot (1) , Debapriya Chaudhuri (6) , Hongxin Yang (7) , Mairbek Chshiev (6) , Changping Yang (2) , Bin Zhou (2) , Jinghuai Fang (3) , Stéphane Mangin (1) , Yuan Lu (1)

1 IJL - Institut Jean Lamour
2 Hubei University
3 Nantong University
4 UCCS Équipe Couches Minces & Nanomatériaux
5 USTC - University of Science and Technology of China [Hefei]
6 SPINTEC - SPINtronique et TEchnologie des Composants
7 NIT - Ningbo Institute of Technology

The ferroelectric control of spin-polarization at ferromagnet (FM)/ferroelectric organic (FE-Org) interface by electrically switching the ferroelectric polarization of the FE-Org has been recently realized in the organic multiferroic tunnel junctions (OMFTJs) and gained intensive interests for future multifunctional organic spintronic applications. Here, we report the evidence of ferroelectric “ailing-channel” in the organic barrier, which can effectively pin the ferroelectric domain, resulting in nonswitchable spin polarization at the FM/FE-Org interface. In particular, OMFTJs based on $La_{0.6}$$Sr_{0.4}$Mn$O_{3}$/P(VDF-TrFE) (t)/Co/Au structures with different P(VDF-TrFE) thickness (t) were fabricated. The combined advanced electron microscopy and spectroscopy studies clearly reveal that very limited Co diffusion exists in the P(VDF-TrFE) organic barrier when the Au/Co electrode is deposited around 80K. Pot-hole structures at the boundary between the P(VDF-TrFE) needle-like grains are evidenced to induce “ailing-channels” that hinder efficient ferroelectric polarization of the organic barrier and result in the quenching of the spin polarization switching at Co/P(VDF-TrFE) interface. Furthermore, the spin diffusion length in the negatively polarized P(VDF-TrFE) is measured to be about 7.2 nm at 20K. The evidence of the mechanism of ferroelectric “ailing-channels” is of essential importance to improve the performance of OMFTJ and master the key condition for an efficient ferroelectric control of the spin polarization of “spinterface”.

Mots clés: tunneling magneto-resistance; spin polarization; spinterface; organic multiferroic tunnel junctions

Domaines: Chimie

Shiheng Liang, Zhongwei Yu, Xavier Devaux, Anthony Ferri, Weichuan Huang, et al.. Quenching of Spin Polarization Switching in Organic Multiferroic Tunnel Junctions by Ferroelectric “Ailing-Channel” in Organic Barrier. ACS Applied Materials & Interfaces, 2018, 10 (36), pp.30614 - 30622. ⟨10.1021/acsami.8b11437⟩. ⟨hal-01874322⟩