Jun Li,Dongpeng Zhao,Han Bai,Zhi Yuan,Zhongxiang Zhou
Magnetic-field induced dynamic magnetoelectric coupling effects and polarization performance of Z-type Sr3Co2Fe24O41 (SCFO) ceramic has been investigated. Results found that SCFO's transverse tapered magnetic structure can induce electric polarization, and its electric polarization direction will not change under external magnetic effects. First-order dynamic magnetoelectric coupling coefficient (α) and second-order dynamic magnetoelectric coupling coefficient (β) of SCFO exhibited strong response main in magnetic structural phase transition region. The magnetoelectric structural phase transition position appeared in low magnetic field, and the magnetic moment vector and its corresponding electric polarization vector of SCFO exhibited the most unstable state near its equilibrium position, which is beneficial for inducing strong dynamic magnetoelectric coupling response. When the applied magnetic fields to SCFO increased, the magnetic moment stability near the equilibrium position increased, and the dynamic magnetoelectric coupling response decreased. Results showed that the dynamic magnetoelectric coupling response of SCFO can bear T1 = 370 K high temperature. The dynamic magnetoelectric coupling response induced by low magnetic fields in SCFO contributes to its actual application in next generation magnetoelectric information storage devices.
Polycrystalline manganites with outstanding anisotropic magnetoresistance and temperature coefficient of magnetization have great potential for application in magnetic sensors. Recent studies have shown that altering the ion occupation ratio would induce Jahn–Teller distortion and affect the spin–orbital coupling effect, consequently enhancing anisotropic magnetoresistance and temperature coefficient of magnetization. In this study, single-phase polycrystalline La0.7−xGdxCa0.3MnO3 ceramics were fabricated via a simple nonaqueous sol–gel technique. The optimal Gd doping concentration induced the strongest Jahn–Teller distortion, as was confirmed through the Curie–Weiss behavior of the ceramics. Finally, these ceramics demonstrated the relatively large anisotropic magnetoresistance and temperature coefficient of magnetization (−30% and −28.1%/K, respectively) values under a low magnetic field of 1 T. The enhanced anisotropic magnetoresistance properties were derived from the spin–orbital coupling effect as demonstrated by the classical transport model.
Inspired by the extraordinary functionality of biological systems that assemble anisotropic nanostructures, there is growing interest in designing multiscale ordered materials to modulate bio-based micro- and nanoscale assemblies for high performance and exceptional functionality. Current strategies for magnetic field-induced alignment of cellulose nanofibers face limitations, often relying on ultra-high magnetic fields or yielding poor orientation with microspherical magnetic particles. This study proposes an ordered assembly of cellulose nanofibers decorated with magnetic nanorods, induced under low magnetic fields. The resulting cellulose films exhibit an orientation parameter greater than 0.8. It demonstrates that the mechanism behind the magnetic field-induced alignment of magnetic nanorods with cellulose nanofibers results from a combination of magnetic torque-induced alignment of the rods and shear orientation driven by radial flow. This highly aligned, magnetically flexible, multiresponsive film achieves a dielectric constant elevated from 8.67 to 15.21. Simply by regulating the cellulose structure, the TENG output performance is improved to 971%. Compared with other complex modified cellulose film methods, the output performance is only enhanced to 760%. This method provides new insights into anisotropic assembly, with potential applications in flexible electronics and self-powered sensors.
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