Engineering of Spin Injection and Spin Transport in Organic Spin Valves Using π‐Conjugated Polymer Brushes

Geng, Rugang; Roy, Anandi; Zhao, Wenbo; Subedi, Ram Chandra; Li, Xiaoguang; Locklin, Jason; Nguyen, Tho Duc

doi:10.1002/adfm.201504201

Cited by 40 publications

(37 citation statements)

References 67 publications

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“…Because the epitaxial growth technology of organic materials on metal surfaces is not available for OSCs thus far, a possible way to control the interface is to chemically grow a self‐assembled monolayer (SAM) on the magnetic electrodes. This type of SAM controlled spinterface effect in π‐conjugated polymer brushes based OSVs has recently been achieved by Geng et al…”

Section: Discussionmentioning

confidence: 90%

Organic Spin Valves: A Review

Devkota

Geng

Subedi

et al. 2016

Adv Funct Materials

Self Cite

108

106

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accelerated impressively and advanced to a range of materials and a number of techniques to verify the successful injection and transport of the SP carriers. [ 1,2,10,11 ] The effect has been realized in a variety of materials combinations such as FM fi lms, FM/anti-FM coupled layers, or FM semiconductors as the injection/detection electrodes and the metals, superconductors, inorganic semiconductors, organic semiconductors, and insulators including ferroelectric and topological insulators as the spacers. [ 1,2,[12][13][14][15][16][17][18] The GMR effect was extensively studied using non-magnetic metallic interlayer and its applications such as electric switching, magnetic recording, and sensors were suggested and employed. [ 1,2,16 ] However, all-metallic spintronic devices imposed restrictions in applications as they are characterized by short spin relaxation time (≈picosecond) and are not suitable for coherent spin manipulation. [ 1,2,19 ] To overcome these limitations, the spintronics community caught its attention towards hybrid devices with semiconductors (SCs) sandwiched in between the FM layers and continued advancing to a range of semiconducting materials. [ 2,14,[20][21][22] The organic semiconductors (OSCs) are among the youngest members of the spacer materials and were fi rst tested in the spintronic devices only about a decade ago. Nevertheless, OSC devices have been of continuously advancing research topics over the past three decades for their rich physics, fl exible chemi stry, cost effi ciency, and potential applications in new generations of electronic devices including organic light emitting diodes (OLEDs), [23][24][25] organic solar cells, [ 26,27 ] and organic fi eld effect transistor. [ 28,29 ] In fact, OLEDs have already revolutionized the modern display industry and spin-dependent devices such as organic spin valves (OSVs), OLED-based magnetic sensors, and spin-OLEDs are under intensive study to achieve their new avenues. [30][31][32] This increasing interest on organic electronics is for their several distinctions over inorganic counterparts. [19][20][21]33,34 ] Electronically, the band theory explains the electric transport in inorganic SCs while charge hopping is the main transport mechanism in the OSCs with much smaller carrier mobility. This is a favorable condition for large electron-hole pair recombination without the need of using a p-n junction structure. [23][24][25] Spintronically, the inorganic SCs contain heavy atoms giving rise to a large spin-orbit coupling (SOC), which is a response of the electron spin degree of freedom to its orbital environment. The strength of the SOC in solids depends upon the nature of orbital wave functions of electrons and the materials structure. [ 35 ] In case of hydrogenic wave-function-like electrons (s-orbital electrons), it is Organic spintronics is an emerging and potential platform for future electronic devices. Signifi cant progress has been made in understanding the spin injection, manipulation, and detection in organic spin valves in the p...

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Section: Discussionmentioning

confidence: 90%

Organic Spin Valves: A Review

Devkota

Geng

Subedi

et al. 2016

Adv Funct Materials

Self Cite

108

106

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show abstract

“…The performances of this type of devices have been compared with those of a similar one obtained by replacing the double decker layer with diamagnetic molecules, the diethyl(11‐iodoundecyl)phosphonate, bearing the same linking group promoting the chemisorption. This strategy has been developed in order to disentangle the effect of the chemical functionalization of the manganite, which has been addressed also in earlier reports, from more specific effects, due to the presence of a layer of magnetic molecules forming an additional spinterface for the spin injection into the OSC.…”

Section: Introductionmentioning

confidence: 99%

Tuning of a Vertical Spin Valve with a Monolayer of Single Molecule Magnets

Cucinotta

Poggini

Pedrini

et al. 2017

Adv Funct Materials

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The synthesis and the chemisorption from solution of a terbium bis-phthalocyaninato complex suitable for the functionalization of lanthanum strontium manganite (LSMO) are reported. Two phosphonate groups are introduced in the double decker structure in order to allow the grafting to the ferromagnetic substrate actively used as injection electrode in organic spin valve devices. The covalent bonding of functionalized terbium bis-phthalocyaninato system on LSMO surface preserves its molecular properties at the nanoscale. X-ray photoelectron spectroscopy confirms the integrity of the molecules on the LSMO surface and a small magnetic hysteresis reminiscent of the typical single molecule magnet behavior of this system is detected on surface by X-ray magnetic circular dichroism experiments. The effect of the hybrid magnetic electrode on spin polarized injection is investigated in vertical organic spin valve devices and compared to the behavior of similar spin valves embedding a single diamagnetic layer of alkyl phosphonate molecules analogously chemisorbed on LSMO. Magnetoresistance experiments have evidenced significant alterations of the magneto-transport by the terbium bisphthalocyaninato complex characterized by two distinct temperature regimes, below and above 50 K, respectively.

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“…Our earlier experimental studies have shown that the spins in ferromagnetic nanoparticles can interact with nearby orbital fields in organic molecules, generating spin–orbital interactions at the ferromagnetic/organic interface . Furthermore, using the ferromagnetic surface represents the most direct approach to inject spins into semiconductors, leading to a spin‐selective interface . In general, the spin‐selective interface requires the direct contact between a ferromagnet and an organic semiconductor by overlapping their orbital wave functions.…”

mentioning

confidence: 99%