Theoretical Investigation of Influence of Mechanical Stress on Magnetic Properties of Ferromagnetic/Antiferromagnetic Bilayers Deposited on Flexible Substrates

Effect of mechanical stress on magnetic properties of an exchange-biased ferromagnetic/antiferromagnetic bilayer deposited on a flexible substrate is investigated. The hysteresis loops with different magnitudes and orientations of the stress can be classified into three types. The corresponding physical conditions for each type of the loop are deduced based on the principle of minimal energy. The equation of the critical stress is derived, which can judge whether the loops show hysteresis or not. Numerical calculations suggest that except for the magnitude of the mechanical stress, the relative orientation of the stress is also an important factor to tune the exchange bias effect.

ANALYSIS ON LAPPING AND POLISHING PRESSURE DISTRIBUTION OF HARD MAGNETIC DISK SUBSTRATE

The contact model of lapping and polishing for magnetic disk substrate is presented. Based on elastic contact theory, pressure distribution for this model are analyzed. Further, the effects of various parameters, such as the material properties of the PVA(polyvinyl acetate),grinding stone, the polishing pad and the base plate, the thickness of the pad or the stone on the pressure distribution have been discussed.

Magnetic Ti_(3)C_(2)T_(x)/Fe_(3)O_(4)/Ag substrate for rapid quantification of trace sulfonamides in aquatic products by surface enhanced Raman spectroscopy

Surface-enhanced Raman scattering(SERS)spectroscopy has been employed as a rapid analysis technology for food security inspection recently.Nowadays,it is still a great challenge to rapidly quantify multiple trace antibiotics potentially abused in aquaculture industry.In this work,a magnetic Ti_(3)C_(2)T_(x)/Fe_(3)O_(4)/Ag substrate was prepared for the development of a reliable rapid SERS quantification method for multiple trace sulfonamides in aquatic products.This magnetic substrate had good uniformity,reproducibility,stability and SERS activity.Moreover,this substrate could integrate the magnetic separation-enrichment and matrix clean-up without cross contamination,which endowed it with good selectivity and antiinterference capability during real sample analysis.The electromagnetic enhancement and chemical enhancement mechanism of this magnetic substrate were studied in detail to reveal its good separationenrichment performance and SERS activity.Finally,a rapid SERS quantification method was established and practically applied for trace phthalic sulfathiazole(PST)and silver sulfadiazine(SSD)in aquatic products by using Ti_(3)C_(2)T_(x)/Fe_(3)O_(4)/Ag magnetic substrates.Trace PST and SSD could be actually detected and quantified as 55.9μg/kg and 64.0μg/kg in aquatic products,respectively.Good recoveries of 83.9%-116%with relative standard deviations(RSDs)of 0.5%-3.2%for PST and 80.2%-102%with RSDs of 1.3%-5.8%for SSD were obtained.This work proposed an efficient and reliable method for rapid quantification of trace multiple sulfonamides in complex aquatic samples during food security inspection.

Enhanced valley polarization in WSe_(2)/YIG heterostructures via interfacial magnetic exchange effect

Exploiting the valley degrees of freedom as information carriers provides new opportunities for the development of valleytronics.Monolayer transition metal dichalcogenides(TMDs)with broken space-inversion symmetry exhibit emerging valley pseudospins,making them ideal platforms for studying valley electronics.However,intervalley scattering of different energy valleys limits the achievable degree of valley polarization.Here,we constructed WSe_(2)/yttrium iron garnet(YIG)heterostructures and demonstrated that the interfacial magnetic exchange effect on the YIG magnetic substrate can enhance valley polarization by up to 63%,significantly higher than that of a monolayer WSe_(2)on SiO_(2)/Si(11%).Additionally,multiple sharp exciton peaks appear in the WSe_(2)/YIG heterostructures due to the strong magnetic proximity effect at the magnetic-substrate interface that enhances exciton emission efficiency.Moreover,under the effect of external magnetic field,the magnetic direction of the magnetic substrate enhances valley polarization,further demonstrating that the magnetic proximity effect regulates valley polarization.Our results provide a new way to regulate valley polarization and demonstrate the promising application of magnetic heterojunctions in magneto-optoelectronics.

Tunable zeroth-order resonator based on a ferrite metamaterial structure

This paper proposes a tunable zeroth-order resonator on a composite right/left-handed transmission line consisting of a transversely magnetized ferrite substrate periodically loaded by microstrip inductors. Based on the propagation theory of edge guided modes, the analysis procedure of this structure is introduced. The numerical results demonstrate the tunability of the resonant frequency by changing the DC bias magnetic field applied to the ferrite. In contrast to previous work, the proposed structure is easy to design and fabricate and does not require a chip component.