Power Dissipation in Spintronic Devices Out of Thermodynamic Equilibrium

Quantum limits of power dissipation in spintronic computing are estimated. A computing element composed of a single electron in a quantum dot is considered. Dynamics of its spin due to external magnetic field and interaction with adjacent dots are described via the Bloch equations. Spin relaxation due to magnetic noise from various sources is described as coupling to a reservoir. Resulting dissipation of energy is calculated and is shown to be much less than the thermal limit, ∼kT per bit, if the rate of spin relaxation is much slower than the switching rate. Clues on how to engineer an energy efficient spintronic device are provided.     

2000年—2001年磁性功能材料研究和应用新进展

综述了磁性功能材料研究和应用在2000年－2001年间的新进展，其内容包括：（1）自旋电子学；（2）Bi-Fe氧化物的磁性；（3）稀有和稀土金属垂直磁记录材料；（4）新的多层膜磁性材料；（5）磁浮列车。     

Single Nanoparticle Magnetic Spin Memristor

There is an increasing demand for the development of a simple Si‐based universal memory device at the nanoscale that operates at high frequencies. Spin‐electronics (spintronics) can, in principle, increase the efficiency of devices and allow them to operate at high frequencies. A primary challenge for reducing the dimensions of spintronic devices is the requirement for high spin currents. To overcome this problem, a new approach is presented that uses helical chiral molecules exhibiting spin‐selective electron transport, which is called the chiral‐induced spin selectivity (CISS) effect. Using the CISS effect, the active memory device is miniaturized for the first time from the micrometer scale to 30 nm in size, and this device presents memristor‐like nonlinear logic operation at low voltages under ambient conditions and room temperature. A single nanoparticle, along with Au contacts and chiral molecules, is sufficient to function as a memory device. A single ferromagnetic nanoplatelet is used as a fixed hard magnet combined with Au contacts in which the gold contacts act as soft magnets due to the adsorbed chiral molecules.     

Magnetization Reversal by Electrical Spin Injection in Ferromagnetic (Ga,Mn)As-Based Magnetic Tunnel Junctions

We report current-induced magnetization reversal in a ferromagnetic semiconductor-based magnetic tunnel junction (Ga,Mn)As/AlAs/(Ga,Mn)As prepared by molecular beam epitaxy on a p-GaAs(001) substrate. A change in magneto-resistance that is asymmetric with respect to the current direction is found with the excitation current of 10⁶ A/cm². Contributions of both unpolarized and spin-polarized components are examined, and we conclude that the partial magnetization reversal occurs in the (Ga,Mn)As layer having smaller magnetization with the spin-polarized tunneling current of 10⁵ A/cm².     

Structural Control of Rashba Spin–Orbit Coupling in In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As Quantum Wells

We investigated the correlation between the Rashba spin–orbit coefficient and potential shape of the quantum wells (QW), where values are experimentally deduced from the weak antilocalization analysis. We studied the gate I–V properties of the QW samples and have obtained results consistent with the potential shapes predicted for these QWs.     

晶体管的新概念

简要介绍了几种晶体管,包括柔性晶体管、单原子晶体管、单电子晶体管、单自旋晶体管、量子力学晶体管、谐振隧穿晶体管、薄膜晶体管、透明晶体管和纳米晶体管的新概念。     

Electric Field Induced Suppression of the Magnetoresistance of Dilute Magnetic Semiconductor Trilayers

In semiconductor spintronic devices, the semiconductor is usually lightly doped and nondegenerate, and moderate electric fields can dominate the carrier motion. We recently derived a drift-diffusion equation for spin polarization in the semiconductors by consistently taking into account electric-field effects and nondegenerate electron statistics and identified a high-field diffusive regime that has no analog in metals. Here high fields are argued to substantially reduce the magnetoresistance observable in a recent experiment on magnetic-semiconductor–nonmagnetic-semiconductor–magnetic-semiconductor trilayers.     

Spintronics: Sources and Challenge. Personal Perspective

Spintronics emerged very recently as a quickly developing interdisciplinary field in the framework of solid-state physics with tempting technological perspectives. This promise is based on the active involvement of the electron spin, side by side with its charge, in the operation of nanometer scale electronic devices. It is a remarkable feature of spintronics that it is growing coherently from several different fields of solid-state physics (semiconductor physics, magnetism, superconductivity, etc.) and involves a multiplicity of rather diversified phenomena. This unique property of spintronics makes it a fascinating field for research and applications but also creates a challenge for researchers. In this short note, I concentrate on the physical background of spintronics and some historical roots of it but avoid making specific prognosis about technological applications.