Organic Spin Valves: A Review

Abstract

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...

Magnetoresistance and Spinterface of Organic Spin Valves Based on Diketopyrrolopyrrole Polymers

“…Figure 4a shows the temperature dependence of the MR ratios for PTDCNTVT-420-based spin valves using Py as the top electrode. As shown in Figure 4b, the MR ratios of the devices using the Py electrodes are higher than those using the Co electrodes except at 200 K, and the MR ratios decreased much sharper than Co may be originated from the lower Curie temperature (T c ) [22] of the Py which affects the hybrid spin interface and the surface spin-polarization. On the other hand, spin valve devices using the Py electrodes showed the signal-to-noise ratio better than that of the corresponding devices with Co as the top electrodes (compared to Figure 2b).…”

“…Electron. P of Py (45%) is higher than that of Co (34%), [22] and this difference can result in better MR behavior of the OSVs using the Py electrodes. 2019, 5,1900318 www.advelectronicmat.de ratios measurement results are given in Figure 4c.…”

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recombination in organic light-emitting diodes and organic magnetoresistance (MR) devices. [13][14][15][16][17][18][19][20] The most common prototype organic device using spin freedom is organic spin valves (OSVs), [5,11,[21][22][23][24][25] which consist of a nonmagnetic spacer sandwiched between two ferromagnetic (FM) electrodes, and based on the alignment of the electron spin relative to the FM layer magnetization orientation. [13][14][15][16][17][18][19][20] The most common prototype organic device using spin freedom is organic spin valves (OSVs), [5,11,[21][22][23][24][25] which consist of a nonmagnetic spacer sandwiched between two ferromagnetic (FM) electrodes, and based on the alignment of the electron spin relative to the FM layer magnetization orientation.

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Hybrid Interfaces in Molecular Spintronics

“…Thus, organic light emitting diodes (OLED) devices based on molecules or polymers have already become available to consumers and have found applications in displays and lighting, while organic photovoltaic devices are becoming competitive with respect to silicon devices in terms of low cost production and flexibility . More recently, molecular spintronic devices have also entered in the game with the aim of fabricating a second generation of devices for hard drive information storage and magnetic sensing …”

“…Several special issues and some reviews dealing with different aspects of molecular spintronics have been previously reported which are devoted for instance to the spin‐transport in organic semiconductors,,, the miniaturization to single‐molecule spintronics (nanospintronics), the advances and comparison between both branches of the field or to the unravelling and comprehension of interface effects ,,. In this account we will focus on organic spintronics and, in particular in the study of hybrid interfaces affording unusual or even new properties to the device (such as spin filtering effects, unusually large working voltages, or a response to external stimuli).…”