Electron transport and noise spectroscopy in organic magnetic tunnel junctions with PTCDA and Alq3 barriers

Isidoro Martinez, Juan Pedro Cascales, Jhen-Yong Hong, Minn-Tsong Lin, Mirko Prezioso, Alberto Riminucci, Valentin A. Dediu, Farkhad G. Aliev, "Electron transport and noise spectroscopy in organic magnetic tunnel junctions with PTCDA and Alq3 barriers", Spintronics IX, Proc. SPIE 9931 (4 November 2016); doi: 10.1117/12.2237721. Copyright 2016 Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibitedProceedings of IX Spintronics Conference ( San Diego, California, United States)The possible influence of internal barrier dynamics on spin, charge transport and their fluctuations in organic spintronics remains poorly understood. Here we present investigation of the electron transport and low frequency noise at temperatures down to 0.3K in magnetic tunnel junctions with an organic PTCDA barriers with thickness up to 5 nm in the tunneling regime and with 200 nm thick Alq 3 barrier in the hopping regime. We observed high tunneling magneto-resistance at low temperatures (15-40%) and spin dependent super-poissonian shot noise in organic magnetic tunnel junctions (OMTJs) with PTCDA. The Fano factor exceeds 1.5-2 values which could be caused by interfacial states controlled by spin dependent bunching in the tunneling events through the molecules. 1 The bias dependence of the low frequency noise in OMTJs with PTCDA barriers which includes both 1/f and random telegraph noise activated at specific biases will also be discussed. On the other hand, the organic junctions with ferromagnetic electrodes and thick Alq 3 barriers present sub-poissonian shot noise which depends on the temperature, indicative of variable range hoppingSupport by UAM-Santander collaborative project (2015/ASIA/04) as well as by the Spanish MINECO (MAT2012-32743 and MAT2015-66000-P) grants and the Comunidad de Madrid through NANOFRONTMAG (S2013/MIT-2850) is also gratefully acknowledged. J.P.C. acknowledges support from the Fundacion Seneca (Region de Murcia) posdoctoral fellowship (19791/PD/15

Depth Profiling Photoelectron-Spectroscopic Study of an Organic Spin Valve with a Plasma-Modified Pentacene Spacer

[[abstract]]We report an enhanced magnetoresistance (MR) in an organic spin valve with an oxygen plasma-treated pentacene (PC) spacer. The spin valve containing PC without the treatment shows no MR effect, whereas those with moderately plasma-treated PC exhibit MR ratios up to 1.64% at room temperature. X-ray photoelectron spectroscopy with depth profiling is utilized to characterize the interfacial electronic properties of the plasma-treated PC spacer which shows the formation of a derivative oxide layer. The results suggest an alternative approach to improve the interface quality and in turn to enhance the MR performance in organic spin valves.[[incitationindex]]SCI[[booktype]]電子