Microwave Magnetoresistance and Microwave Absorption in Sr₂FeMoO₆

Abstract

We report the direct current (dc) magnetoresistance and microwave magnetoresistance (MWMR) as a function of frequency (f = 0.5−3 GHz), along with microwave absorption ( f = 0.01−4.2 GHz) in Sr 2 FeMoO 6 (SFMO) synthesized by a wet chemical method. Magnetization data indicates that the onset temperature of ferromagnetism in this sample is above 400 K. The resistivity of SFMO shows semiconducting behavior under dc magnetic fields of H = 0 and 30 kOe. The MWMR in this highly resistive SFMO is determined by coating a layer of silver paint on the upper surface of the sample to guide the microwave (MW) signal and measuring the magnetoimpedance of the silver paint. As H is increased from 0 to 2.2 kOe, the MWMR smoothly decreases for f < 1.2 GHz, whereas it changes sign from negative to positive and exhibits a peak at H = H res for higher frequencies, and the peak migrates to a higher field value as f increases. The magnitude of MWMR at the peak reaches a maximum value of 17.9% for 3 GHz at a low field of H = 900 Oe, a value much larger than the room temperature dc magnetoresistance at the same field. We argue that the observed MWMR of the Ag layer reflects the spin dynamics in SFMO. The field dependence of MW power absorption measured using a vector network analyzer shows features similar to MWMR, which confirms that MWMR is caused by the current-induced resonant excitation of the exchange-coupled spins (ferromagnetic resonance) in the sample. The microwave current-driven ferromagnetic resonance reported here in polycrystalline SFMO is compared with a similar phenomenon reported recently in ferromagnetic nonmetal bilayer thin films.

The emerging Sr2FeMoO6-based electrocatalysts for solid oxide electrochemical cell: synthesis, modulation and applications

“…The grain size, ADs, and oxygen vacancy concentrations of perovskite oxides were controlled by modulating the synthesis conditions of the sol-gel method (e.g., pH, temperature, gas flow rate) to promote its application in electrocatalysis by improving the intrinsic properties and structure of the materials. At the same time, it is worth noting that the magnetization intensities of SFM catalysts prepared by different preparation methods are different [23,54,57] . This may mean that improving the spin of Fe in SFM by specific methods (e.g., atomic doping, lattice strain, and magnetic field coordination) could reduce the chemical reaction energy barrier and promote the occurrence of reactions.…”

“…SFM electrocatalysts can be prepared via the sol-gel method, the citrate self-combustion method, the solidstate reaction method, the chemical coprecipitation method, the hydrothermal method, and the metal-organic salt thermal breakdown in the organic solvent. Thin film SFM catalyst can be prepared using the chemical spray thermal deposition and the laser pulse deposition methods [20,21,[23][24][25][26][27] . Traditionally, SFM electrocatalysts have been generated by solid-state reactions, but the shape and grain size of SFM electrocatalysts prepared in this manner are difficult to control [28,29] .…”

Fabrication and Microwave Absorption Properties of FeSiAl@PANI Composites

“…The ensuing problems of electromagnetic interference and leakage are constantly troubling people, while electromagnetic radiation poses a serious hazard to mankind’s health. , Microwave-absorbing materials (MAMs) have the ability to convert incident electromagnetic waves into heat or consume them through interference by a series of loss mechanisms (dielectric loss, magnetic loss, etc. ). , In practical applications, absorbing materials should meet the characteristics of low density, large effective absorption bandwidth (EAB), small thickness, and high reflection loss (RL). , Therefore, extensive research has been conducted on MAMs to mitigate electromagnetic pollution by designing efficient materials.…”