The origin of interfacial electronic and magnetic degradation for a ferromagnet atop organic conjugated molecules

Hsu, Yao-Jane; Hung, Ying; Lin, Ying-Chang; Lai, Yi‐Chun; Chang, Hwan‐You; Wang, Chia-Hao; Chan, Yuan-Li; Hsia, Ching-Lun; Luo, Meng Fan; Lee, Chih‐Hao; Wei, Der-Hsin

doi:10.1016/j.synthmet.2010.12.023

Cited by 12 publications

(4 citation statements)

References 26 publications

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“…The interfacial SP role at the top contact of a FM atop an OSC is, however, still unknown and more complicated because penetration, diffusion, and reaction of a metal occur at the ill-defined interface [13,[34][35][36]. In the worst case, for a fragile OSC, the reaction might modify or damage the molecular structures and yield degraded electronic and magnetic properties [37], Only a MR response is hence mea sured for fragile organic molecules in a planar-type OSV [38], The situation might differ completely if the molecules contain an appropriate functional group that can resist degradation and become spin polarized. As the top FM in an OSV using Alq3 as a nonmagnetic spacer directly controls the performance of the device [9], we examined the electronic structures of the interfacial region and the SP of Alq3-C o top bilayers to seek the criteria of organic molecules effective for spintronics.…”

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Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atopAlq3

et al. 2015

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The spin polarization of organic-ferromagnetic interfaces in an organic spin valve critically affects the efficiency of spin injection or detection. We examined the chemical and electronic properties of ferromagnetic Co deposited on organic Alq3 and the interfacial spin-polarized capability of the electronic states. Our x-ray photoemission spectra and calculations with density-functional theory indicate a sequential and unequal distribution of charge from Co clusters to N and then to O atoms in Alq3. The preferential orbital hybridization at specific functional sites produces efficient spin polarization of organic molecules. Element-specific measurements of x-ray magnetic circular dichroism demonstrate the preferential spin polarization in the lowest unoccupied molecular orbital state of N atoms at the complex interface for Co atop Alq3, which agrees satisfactorily with calculation. Our results indicate that an induced interfacial spin polarization on engineering the dominant reaction of Co with mainly N and O atoms in Alq3 might pave a way for effective spin filtering in organic spintronics.PACS number(s): 79.60. Fr, 75.70.Cn, 68.35.Fx, 75.76.+j Organic spin valves (OSV) in which an organic semicon ductor (OSC) spacer is sandwiched between two ferromagnetic (FM) electrodes have attracted much attention because of an enduring spin coherence of organic materials via weak spin-orbit coupling [1], Dediu et al. pioneered in achiev ing magnetoresistance (MR) up to 30% near 295 K in a LaovSrojMnOsfLSMOj/sexithiophenefTgj/LSMO OSV, ini tiating a great potential of organic-based spintronics [2], Xiong et al. subsequently made a remarkable observation of a giant MR at 40% at 11 K in a LSMO/Alq3/CoOSV [1], Among the most widely used OSC in OSV, tri(8-hydroxyquinoline) aluminum (Alq3) composed of 7r-conjugated molecules is considered to be a promising material for effective spin transport because of its great spin-relaxation time and unique molecular structure [1,3-6], The combination of Alq3 and d -band FM Co has achieved striking MR values [1,7-12], Although an ill-defined layer between Alq3 and top Co was manifested at an Alq3 thickness greater than 100 nm, it is one of few examples in which an OSV displayed a large MR [1], Such an ill-defined layer is ascribed to the diffusion of metal into a soft organic layer, which might be related to the disputed results of the MR sign and mechanism [1,12-15], To prevent the unexpected interdiffusion and chemical interaction at the interfacial region, a buffer layer inserted between the top Co and Alq3 has improved the device performance [9,16-18]. Although metal interdiffusion is preventable with those meth ods, it might not provide a deep understanding of the lacking essential mechanisms [19][20][21]. Moreover, in the case of an OSV with no buffer layer, a large MR was still achieved [1,8]. Various techniques have been used to engineer, to control, or to detect the efficient spin injection and transport [ 1,4,22,23] 'jenghan @ on traditionally applying a specific bias voltage to...

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Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atopAlq3

et al. 2015

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“…The X-ray photoelectron spectroscopy (XPS) experiments were performed using 24A1 and 09A2 beamlines at the National Synchrotron Radiation Research Center (NSRRC), Hsinchu, Taiwan. 39 Fourier-transform infrared spectrometer (FTIR) measurements were made using a Bruker Vertex 80v spectrometer in attenuated total reflection (ATR) mode at the Instrumentation Center at National Tsing Hua University, Taiwan. To demonstrate the spectra changes at various GO and ErGO concentrations, transmittance spectra were obtained using a UV-vis spectrophotometer (U-2900, Hitachi High-Technologies Corporation, Japan) with a wavelength from 200 to 1100 nm at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Real-time and stepwise deoxidization processes to tune the photoluminescence properties of graphene oxide using EC-SPR spectroscopy

Chiu

Yang

2018

RSC Adv.

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“…28–38 More importantly, these metal–organic semiconductors are adsorbed on the surface with their macrocyclic core parallel to the substrate, rather than in sterically-standing arrangements. So far, only a few steric adsorbed metal–organic semiconductors have been reported 39,40 showing strong magnetic interaction via a longer redox distance between the central metal and the substrate (Table S1, ESI†), which intrigued and motivated us to carry out the current investigation.…”

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Unravelling the strong interplay for interfacial magnetic switching in metal–organic-based spintronics

Chen,

Yu,

Lin

et al. 2024

J. Mater. Chem. C

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The origin of interfacial electronic and magnetic degradation for a ferromagnet atop organic conjugated molecules

Cited by 12 publications

References 26 publications

Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atopAlq3

Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atopAlq3

Real-time and stepwise deoxidization processes to tune the photoluminescence properties of graphene oxide using EC-SPR spectroscopy

Unravelling the strong interplay for interfacial magnetic switching in metal–organic-based spintronics

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