Spin‐Dependent Processes Measured without a Permanent Magnet

Abstract

A novel Hall circuit design that can be incorporated into a working electrode, which is used to probe spin-selective charge transfer and charge displacement processes, is reviewed herein. The general design of a Hall circuit based on a semiconductor heterostructure, which forms a shallow 2D electron gas and is used as an electrode, is described. Three different types of spin-selective processes have been studied with this device in the past: i) photoinduced charge exchange between quantum dots and the working electrode through chiral molecules is associated with spin polarization that creates a local magnetization and generates a Hall voltage; ii) charge polarization of chiral molecules by an applied voltage is accompanied by a spin polarization that generates a Hall voltage; and iii) cyclic voltammetry (current-voltage) measurements of electrochemical redox reactions that can be spin-analyzed by the Hall circuit to provide a third dimension (spin) in addition to the well-known current and voltage dimensions. The three studies reviewed open new doors into understanding both the spin current and the charge current in electronic materials and electrochemical processes.

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

“…The other electrons (or holes) with the opposite spin are backscattered at source electrode decreasing I D by half. Although CISS effect appears detrimental for charge transport, it offers a wealth of new opportunities of which the development of spintronics with no magnets is not the least …”

Spintronics on chiral objects

“…The CISS can accumulate spins in non-magnetic layers that behaves like magnets in which the accumulated spins can be detected by Hall devices 24 . For example, when the Hall bar that is made of two-dimensional electron gas (2DEG) covered by chiral molecules/nanoparticle assembly is exposed to a circularly polarized light, the measured Hall voltage reveals striking contrasts depending on both the handedness of chiral molecules and the sign of circular polarization of the light.…”

Switchable Chiral Metasurface for Terahertz Anomalous Reflection Based on Phase Change Material

“…When x-and y-polarized plane waves are incident, due to the existence of polarization conversion, we obtain the following reflection coefficients of linearly polarized light: r xx , r yx , r yy and r xy . Then, the reflection coefficient of CPL can be obtained by Equation (1). Here, x, y, r and l in the subscript represent x-polarized light, y-polarized light, right-handed circularly polarized light and left-handed circularly polarized light, respectively.…”

“…In the organic world, there are many chiral molecules, such as protein, DNA, sugar molecules, viruses, amino acids and liquid crystals, but there are few chiral structures in nature. Later, it is found that chiral materials can control the spin of electrons to a certain extent [1][2][3]. In addition, thanks to the development of metamaterials, the control of the spin of photons has been realized [4][5][6][7][8][9][10].…”