Response of atomic spin-based sensors to magnetic and nonmagnetic perturbations

Searches for pseudo-magnetic spin couplings require implementation of techniques capable of sensitive detection of such interactions. While Spin-Exchange Relaxation Free (SERF) magnetometry is one of the most powerful approaches enabling the searches, it suffers from a strong magnetic coupling, deteriorating the pseudo-magnetic coupling sensitivity. To address this problem, here, we compare, via numerical simulations, the performance of SERF magnetometer and noble-gas-alkali-metal co-magnetometer, operating in a so-called self-compensating regime. We demonstrate that the co-magnetometer allows reduction of the sensitivity to low-frequency magnetic fields without loss of the sensitivity to nonmagnetic couplings. Based on that we investigate the responses of both systems to the oscillating and transient spin perturbations. Our simulations reveal about five orders of magnitude stronger response to the neutron pseudo-magnetic coupling and about three orders of magnitude stronger response to the proton pseudo-magnetic coupling of the co-magnetometer than those of the SERF magnetometer. Different frequency responses of the co-magnetometer to magnetic and nonmagnetic perturbations enables differentiation between these two types of interactions. This outlines the ability to implement the co-magnetometer as an advanced sensor for the Global Network of Optical Magnetometer for Exotic Physics searches (GNOME), aiming at detection of ultra-light bosons (e.g., axion-like particles).

Modeling of Internal Combustion Engine Ignition Systems with a Circuit Containing Fractional-Order Elements

This paper discusses the research and analysis of the dynamics of high-voltage generating systems. The test subject is an ignition system modelled by a set of two induction coils with an open ferromagnetic core that constitutes an ignition coil. The essence of the tests involved the application of magnetic coupling of the fractional order that enabled taking into account the non-idealities of the coils and the connector that implements the ignition point. The paper contains the results of a theoretical analysis, supported by digital simulations. The conducted experiments confirm the purposefulness of the conducted analyses and the possibility of modeling real objects based on circuits with fractional-order elements.

The Cis/Trans Conformation Approach for Tuning the Magnetic Coupling in a Diradical: Isolation of Pure Pyridine-Based Diradical Dianions

Two-electron reductions of 3,3'-bis(2,6-dimesitylpyridin-4-yl)-1,1'-biphenyl 1 with elemental potassium in the absence and presence of 18-c-6 afforded the diradical dianion salts [K+]2•[trans-1]••2– and [K(18-c-6)]+2•[cis-1]••2–, which exhibits trans and cis configurations respectively....

The positive exchange bias property with hopping switching behavior in van der Waals magnet FeGeTe

The magnetic exchange bias effect is one of the representative interlayer magnetic coupling phenomena and is widely utilized in numerous technological applications. However, its mechanism is still elusive even in a simple magnetic bilayered system because of the complex interface magnetic orders. Van der Waals layered magnetic materials may provide an essential platform for deeply understanding the detailed mechanism of the exchange bias owing to its ideal interface structure. Here we first observed the positive exchange-biased anomalous Hall effect (AHE) with a hopping switching behavior in the FeGeTe Van der Waals nano-flakes. After systemically studying the cooling field dependence properties of the exchange bias effect, we propose that the coexistence of stable and frustrated surface magnetization of the antiferromagnetic phase will modify the total interface coupling energy density between the ferromagnetic (FM) and antiferromagnetic (AFM) phases. This model could provide a consistent description for such unusual exchange bias effect based on microspin simulation.

Coupling Independent Operation in Wireless Power Transfer System without Ferrite Usage

The power transfer efficiency and output power of a wireless power transfer (WPT) system are mainly affected by magnetic coupling between the primary and secondary coils. This paper presents a constant-current series-series compensated WPT system. Based on the bifurcation criteria, kcri and Lcri, the splitting zero phase angle (ZPA) frequencies is adopted as the operating frequency. The proposed system remains fully compensated even under coupling variations, and without ferrite. The current and voltage gains at the operating frequency can be estimated through the primary current and voltage. A phase-locked loop circuit is used to track the corresponding ZPA frequency due to the coil positioning variations. Experimental results have shown that the 1-kW of output power with the satisfied efficiency of 96%.