Emerging Spintronic Materials and Functionalities

Abstract

The explosive growth of the information era has put forward urgent requirements for ultra‐high‐speed and extremely efficient computations. In direct contrary to charge‐based computations, spintronics aims to use spins as information carriers for data storage, transmission, and decoding, to help fully realize electronic device miniaturization and high integration for next‐generation computing technologies. Currently, many novel spintronic materials have been developed with unique properties and multi‐functionalities, including organic semiconductors (OSCs), organic‐inorganic hybrid perovskites (OIHPs), and two‐dimensional materials (2DMs). These materials are useful to fulfil the demand for developing diverse and advanced spintronic devices. Herein, we systematically reviewed these promising materials for advanced spintronic applications. Due to the distinct chemical and physical structures of OSCs, OIHPs, and 2DMs, their spintronic properties (spin transport and spin manipulation) were discussed separately. In addition, some multifunctionalities due to photoelectric and chiral‐induced spin selectivity (CISS) were overviewed, including the spin‐filter effect, spin‐photovoltaics, spin‐light emitting devices, and spin‐transistor functions. Subsequently, we presented challenges and future perspectives of using these multifunctional materials for the development of advanced spintronics.This article is protected by copyright. All rights reserved

Challenges and Prospects of Molecular Spintronics

“…MSCs possessing long-spin-lifetime essence should have held unparalleled potential for efficient spin transport at room temperature; however, in current spintronic research, most MSCs regrettably exhibit short spin lifetime (normally lower than μs) and low spin-transport efficiency until now, seriously impeding the mechanism and application exploration in spintronics. , In general terms, two common parameters are employed to describe the spin transport ability of MSCs: spin lifetime (spin relaxation time, τ ) and spin diffusion length ( L s ). L s can be defined as L normals = k normalB T q τ μ where k B is the Boltzmann constant, T is temperature, q is the elementary charge, and μ is the mobility of the MSC films . Accordingly, L s engages with τ and μ , and both of them are closely bound with the molecular chemical and physical structures of MSCs …”

“…Utilizing the spin freedom of electrons for information storage, transmission, and processing has triggered extensive attention ever since the report of the giant magnetoresistance effect, giving rise to the field of spintronics. − In spintronics, employing spintronic materials with long spin lifetimes for spin-related studies is the important foundation to obtain efficient spin transport and spintronic functionalities, which will promote the development of spintronic applications. − Molecular semiconductors (MSCs) with light element composition possess essentially low spin–orbit coupling (SOC) strength, in which spins can preserve their orientations for a relatively long time, making MSCs the ideal candidate to realize highly efficient room-temperature spin transport. − Moreover, the abundant electrical-optical-magnetic properties and flexible tunability of MSCs give them additional unique advantages in studies on complex spinterface effects and innovative multifunctional spintronics. − The spin-related properties and functional applications of MSCs are commonly investigated and demonstrated by spintronic devices. , In these devices, the spin injection, transport processes, and functionalities all closely related to spintronic properties of MSCs are always the most fundamental and concerned research contents in spintronics, which are also the most important components of the emerging field of molecular spintronics. ,, …”

“…Over the past decades, research on molecular spintronics has been booming, and lots of efforts and great progress have been made in the above research directions. ,,,− However, in fact, the development of this field is still at a relatively primary stage; unclear spin-related theories and scarce spintronic materials and devices make this field step into a bottleneck period of difficulty to improve spin-related performances and achieve innovative multifunctionalities. ,, The concrete key scientific problems causing the tough status are focused on the following aspects. First, from the view of MSCs, the correlations between the chemical and physical structures of MSCs and spin relaxation and transport are unclear, leading it difficult to design and select appropriate and highly efficient MSCs for spintronic applications . Second, there still exists some ambiguous perceptions regarding the ferromagnetic (FM)/MSCs interface properties, including their working principles, influence factors, and controllability .…”

“…Digging deep and clear interfacial mechanisms, and further utilizing their controllable properties as a basis to improve spin injection efficiency or develop functionalities are still very challenging . Third, for spintronic functionalities and their applications, how to improve the performance of already reported functional spintronic devices and explore novel functionalities should be given more attention. , The resolution of all the above scientific problems in molecular spintronics is inseparable from adequately taking advantage of MSCs, and thus designing or selecting ideal spintronic MSCs and devices should be widely concerned. , …”

Tuning d-orbitals to control spin–orbit coupling in terminated MXenes

“…5,6,10–14 This dissipationless way of electron transport has great potential in the applications of low-power and multifunctional spintronic devices. 15,16 Recently, theoretical predictions have identified diverse MXene monolayers as potential 2D TIs, with their surfaces primarily terminated by oxygen (O) and fluorine (F) groups. 17–27 However, due to the relativistic effect, 2D MXene TIs with a large spin–orbit coupling (SOC) effect have mostly been limited to materials with heavy elements.…”