We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, ext...We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon–magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power.展开更多
Sewage sludge is a potential precursor for biochar production,but its effective utilization involves costly activation steps.To modify biochar properties while ensuring cost-effectiveness,we examined the feasibility o...Sewage sludge is a potential precursor for biochar production,but its effective utilization involves costly activation steps.To modify biochar properties while ensuring cost-effectiveness,we examined the feasibility of using seawater as an agent to activate biochar produced from sewage sludge.In our proof-of-concept study,seawater was proven to be an effective activation agent for biochar production,achieving a surface area of 480.3 m^(2)/g with hierarchical porosity distribution.Benefited from our design,the catalytic effect of seawater increased not only the surface area but also the graphitization degree of biochar when comparing the pyrolysis of sewage sludge without seawater.This leads to seawater activated biochar electrodes with lower resistance,higher capacitance of 113.9 F/g comparing with control groups without seawater.Leveraging the global increase in the salinity of groundwater,especially in coastal areas,these findings provide an opportunity for recovering a valuable carbon resource from sludge.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 52471200, 12174165, and 52201219)。
文摘We utilize conventional wave-vector-resolved Brillouin light scattering technology to investigate the spin wave response in YIG thin films under high-power microwave excitation. By varying the microwave frequency, external bias magnetic field, and in-plane wave vector, in addition to observing the dipole-exchange spin waves excited by parallel parametric pumping, we further observe broadband spin wave excitation within the dipole-exchange spin wave spectrum. This broadband excitation results from the combined effects of parallel and perpendicular parametric pumping, induced by irregularities in the excitation geometry, as well as magnon–magnon scattering arising from the absence of certain spin wave modes. Our findings offer new insights into the mechanisms of energy dissipation and relaxation processes caused by spin wave excitation in magnetic devices operating at high power.
基金This research was supported by the National Natural Science Foundation of China(Grant No.51778165)Key Program of National Natural Science of China(Grant No.51638005)+2 种基金Science and Technology Development Fund,Macao Special Administrative Region,China(File No.FDCT-0104/2018/A3,FDCT-0057/2019/A1)Start-up Research Grant of University of Macao(Grant No.SRG2018-00110-FST)the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.[T21-604/19-R]).
文摘Sewage sludge is a potential precursor for biochar production,but its effective utilization involves costly activation steps.To modify biochar properties while ensuring cost-effectiveness,we examined the feasibility of using seawater as an agent to activate biochar produced from sewage sludge.In our proof-of-concept study,seawater was proven to be an effective activation agent for biochar production,achieving a surface area of 480.3 m^(2)/g with hierarchical porosity distribution.Benefited from our design,the catalytic effect of seawater increased not only the surface area but also the graphitization degree of biochar when comparing the pyrolysis of sewage sludge without seawater.This leads to seawater activated biochar electrodes with lower resistance,higher capacitance of 113.9 F/g comparing with control groups without seawater.Leveraging the global increase in the salinity of groundwater,especially in coastal areas,these findings provide an opportunity for recovering a valuable carbon resource from sludge.
