Thirty years of effort in semiconductor quantum dots has resulted in significant developments in the control of spin quantum bits (qubits). The natural two-energy level of spin states provides a path toward quantum information processing. In particular, the experimental implementation of spin control with high fidelity provides the possibility of realizing quantum computing. In this review, we will discuss the basic elements of spin qubits in semiconductor quantum dots and summarize some important experiments that have demonstrated the direct manipulation of spin states with an applied electric field and/or magnetic field. The results of recent experiments on spin qubits reveal a bright future for quantum information processing.

Recently, spin-momentum-locked topological surface states (SSs) have attracted significant attention in spintronics. Owing to spin-momentum locking, the direction of the spin is locked at right angles with respect to the carrier momentum. In this paper, we briefly review the exotic transport properties induced by topological SSs in topological-insulator (TI) nanostructures, which have larger surface-to-volume ratios than those of bulk TI materials. We discuss the electrical spin generation in TIs and its effect on the transport properties. A current flow can generate a pure in-plane spin polarization on the surface, leading to a current-direction-dependent magnetoresistance in spin valve devices based on TI nanostructures. A relative momentum shift of two coupled topological SSs also generates net spin polarization and induces an in-plane anisotropic negative magnetoresistance. Therefore, the spin-momentum locking can enable the broad tuning of the spin transport properties of topological devices for spintronic applications.

Diluted ferromagnetic semiconductors (DMSs) that combine the properties of semiconductors with ferromagnetism have potential application in spin-sensitive electronic (spintronic) devices. The search for DMS materials exploded after the observation of ferromagnetic ordering in Ⅲ-V (Ga,Mn)As films. Recently, a series of DMS compounds isostructural to iron-based superconductors have been reported. Among them, the highest Curie temperature T_C of 230 K has been achieved in (Ba,K)(Zn,Mn)₂As₂. However, most DMSs, including (Ga,Mn)As, are p-type, i.e., the carriers that mediate the ferromagnetism are holes. For practical applications, DMSs with n-type carriers are also advantageous. Very recently, a new DMS Ba(Zn,Co)₂As₂ with n-type carriers has been synthesized. Here we summarize the recent progress on this research stream. We will show that the homogeneous ferromagnetism in these bulk form DMSs has been confirmed by microscopic techniques, i.e., nuclear magnetic resonance (NMR) and muon spin rotation (μSR).

The voltage control of magnetism has attracted intensive attention owing to the abundant physical phenomena associated with magnetoelectric coupling. More importantly, the techniques to electrically manipulate spin dynamics, such as magnetic anisotropy and ferromagnetic resonance, are of great significance because of their potential applications in high-density memory devices, microwave signal processors, and magnetic sensors. Recently, voltage control of spin waves has also been demonstrated in several multiferroic heterostructures. This development provides new platforms for energy-efficient, tunable magnonic devices. In this review, we focus on the most recent advances in voltage control of ferromagnetic resonance and spin waves in magnetoelectric materials and discuss the physical mechanisms and prospects for practical device applications.

Magnetization manipulation by an electric field (E-field) in ferromagnetic/ferroelectric heterostructures has attracted increasing attention because of the potential applications in novel magnetoelectric devices and spintronic devices, due to the ultra-low power consumption of the process. In this review, we summarize the recent progress in E-field controlled magnetism in ferromagnetic/ferroelectric heterostructures with an emphasis on strain-mediated converse magnetoelectric coupling. Firstly, we briefly review the history, the underlying theory of the magnetoelectric coupling mechanism, and the current status of research. Secondly, we illustrate the competitive energy relationship and volatile magnetization switching under an E-field. We then discuss E-field modified ferroelastic domain states and recent progress in non-volatile manipulation of magnetic properties. Finally, we present the pure E-field controlled 180° in-plane magnetization reversal and both E-field and current modified 180° perpendicular magnetization reversal.

Over the past few decades, spin detection and manipulation at the atomic scale using scanning tunneling microcopy has matured, which has opened the possibility of realizing spin-based functional devices with single atoms and molecules. This article reviews the principle of spin polarized scanning tunneling microscopy and inelastic tunneling spectroscopy, which are used to measure the static spin structure and dynamic spin excitation, respectively. Recent progress will be presented, including complex spin structure, magnetization of single atoms and molecules, as well as spin excitation of single atoms, clusters, and molecules. Finally, progress in the use of spin polarized tunneling current to manipulate an atomic magnet is discussed.

Antiferromagnets offer considerable potential for electronic device applications. This article reviews recent demonstrations of spin manipulation in antiferromagnetic devices using applied electrical currents. Due to spin-orbit coupling in environments with particular crystalline or structural symmetries, the electric current can induce an effective magnetic field with a sign that alternates on the lengthscale of the unit cell. The staggered effective field provides an efficient mechanism for switching antiferromagnetic domains and moving antiferromagnetic domain walls, with writing speeds in the terahertz regime.

In this review article, the recent experimental and theoretical research progress in Bi₂Se₃- and Bi₂Te₃-based topological insulators is presented, with a focus on the transport properties and modulation of the transport properties by doping with nonmagnetic and magnetic elements. The electrical transport properties are discussed for a few different types of topological insulator heterostructures, such as heterostructures formed by Bi₂Se₃- and Bi₂Te₃-based binary/ternary/quaternary compounds and superconductors, nonmagnetic and magnetic metals, or semiconductors.

Molecular spintronics is an emerging field which evoked wide research attention since the first molecule-based spintronic device has been reported at 2002. Due to the active study over the last few years, it is found that the interfaces in spintronic device, so called spinterface, is of critical importance for many key issues in molecular spintronics, such as enhancing spin injection, lengthening spin transport distance, as well as manipulating spin signals in molecular spintronic devices. Here in this review, recent studies regarding spinterface in molecular devices, especially those impressive efforts devoted on spin manipulation, have been systematically summarized and discussed.