Nonlinear magnetoelectric effects in Al-substituted strontium hexaferrite

Abstract

This report is on the observation and theory of electric field E induced non-linear magnetoelectric (NLME) effects in single crystal platelets of ferrimagnetic M-type strontium aluminum hexagonal ferrite. Using microwave measurement techniques, it was found that a DC electric field along the hexagonal c-axis results in significant changes in the saturation magnetization and uniaxial magneto-crystalline anisotropy field and these changes are proportional to the square of the applied static electric field. The NLME effects were present with or without an external bias magnetic field. The E-induced variation in magnetic order parameters is attributed to weakening of magnetic exchange and spin–orbit interactions since conduction electrons in the ferrite are effectively excluded from both interactions while being in transit from one Fe ion to another. We present a phenomenological theory which considers magneto-bielectric effects characterized by a quadratic term in electric field E in the free energy density. The coefficients for the NLME coupling terms have been calculated from experimental data and they do show variations with the Al substitution level and the largest rates of change of the saturation magnetization and anisotropy constant change with the applied power were observed for x = 0.4. It was also clear from the study that strength of the NLME effect does not depend on the amount Al substitution, but critically depends on the electrical conductivity of the sample with the highest NLME coefficients estimated for the sample with the highest conductivity. Results of this work are of importance for a new family of electric field tunable, miniature, high frequency ferrite devices.

Electric Field Tuning of a Nickel Zinc Ferrite Resonator by Non-Linear Magnetoelectric Effects

“…Hence, if Δ(4πM0) is linearly proportional to the applied power [21][22][23][24], then the shift Δfr also should be proportional to P which agrees with the results in Fig. 7.…”

“…Studies on c-plane single crystals of (Sr,Al)-and Ba-hexaferrites also revealed a similar NLME effects for currents either in the c-plane or along the c-axis [23,24]. E-tunable resonators and filters of M-and Y-type hexagonal ferrites operating at 12-50 GHz were demonstrated [25][26][27].…”

Structural Elucidation and Evaluation of Magnetic and Dielectric Properties of Lu–La Co‐substituted M‐Type Hexagonal Ferrites Synthesized by Chemical Co‐precipitation Method

“…In ferrite, Fe 3+ on the lattice transforms into Fe 2+ . [ 39 ] During this transformation, the jumping of electrons induces a conductive phenomenon. When the frequency of the jumping electrons aligns with the frequency of the applied electric field, the dielectric loss undergoes a sudden change.…”

Role of thermal and reactive oxygen species-responsive synthetic hydrogels in localized cancer treatment (bibliometric analysis and review)

“…6,26 For instance, preoperative and postoperative neoadjuvant chemotherapy with doxorubicin (DOX) and anthracycline, lacking a delivery mechanism, induces cardiac side effects and adverse reactions in patients with breast cancer. 27 These drawbacks have spurred the development of smart drug delivery systems like hydrogels, nano-vesicles, liposomes, and microneedles for controlled local release. 28,29 Lately, hydrogel delivery systems have gained attention due to their ability to minimize toxic drug effects while demonstrating excellent controlled release and biodegradability.…”