Measurement Of Spin Currents Research Articles

Sensitive Chirality Measurements with Electrical Readout Utilizing the CISS Effect

AbstractChirality is a fundamental chemical property that can be found in almost all aspects of life. Generally, in nature chirality exists in only one of the possible enantiomeric forms. Bitter experience showed that chiral drugs having the same chemical composition but opposite chirality may have extremely different biological effects. It is therefore that detecting and quantifying chirality is important in multiple fields ranging from analytical and biological chemistry to pharmacology, biotechnology, and fundamental physics. To date, the most widely used analytical methods for chiral detection, remain the traditional approaches of measuring circular dichroism and optical rotation. However, these methods suffer from low signal‐to‐noise due to large time‐dependent backgrounds and require complicated optical setups. Recent works associate circular dichroism measurements with the Chiral Induced Spin Selectivity (CISS) spin current measurements. The CISS effect relates the probability of electron spin transmission through chiral molecules to chirality. Depending on the handedness of the molecule, electrons of a certain spin can traverse the molecule more easily in one direction than in the other. It is therefore that the CISS effect could be utilized to electronically measure chirality using spin currents and spin induced dipoles. The review summarizes the different approaches for utilizing the CISS effect for electrical measurements of chirality. Starting with a Hall device that can measure the chirality of the lowest energetic CD band of a monolayer in dry or wet systems. Presenting an enhancement of the effect as well as achieving a wider CD spectrum using electrical gating. Going down to 100 molecules limit with full spectrum response utilizing electro‐optical nano floret devices.

Spin Pumping and Measurement of Spin Currents in Optical Superlattices.

We report on the experimental implementation of a spin pump with ultracold bosonic atoms in an optical superlattice. In the limit of isolated double wells, it represents a 1D dynamical version of the quantum spin Hall effect. Starting from an antiferromagnetically ordered spin chain, we periodically vary the underlying spin-dependent Hamiltonian and observe a spin current without charge transport. We demonstrate a novel detection method to measure spin currents in optical lattices via superexchange oscillations emerging after a projection onto static double wells. Furthermore, we directly verify spin transport through insitu measurements of the spins' center-of-mass displacement.

Influence of electrically induced refraction and absorption on the measurement of spin current by pockels effect in GaAs

The pockels effect could be utilized to measure spin current in semiconductors for linear electro-optic coefficient can be induced by spin current. When dc electric field is applied, the carriers will shift in k space, which could lead to the change of refraction and absorption coefficients. In this paper, we investigate the influence of the induced change of the refraction and absorption coefficients on the measurement of spin current by pockels effect in GaAs.

Measurement of pure spin currents in semiconductors

A new field has emerged called spintronics (spin-based electronics), where the spin of electrons rather than the charge carries information. This may offer opportunities for a new generation of electronic devices. Measuring spin currents in semiconductors plays a key role in spintronics. In this review article, starting from the basic properties of spin currents and the current experimental techniques for spin current measurements, we briefly introduce our theory on optical effects of spin currents in the direct-gap semiconductors, i.e., the Faraday rotation and nonlinear optics, which provide a direct measurement of pure spin currents in semiconductors.