This Faculty Early CAREER award funds research to investigate the magnetization dynamics and damping of magnetic nanostructures. We have extended our broadband ferromagnetic resonance capabilities to enable parallel pumping experiments. We have investigated the relaxation in synthetic antiferromagnet (SAF) systems in proximity to a free layer. This has resulted in the discovery of additional unidirectional resonant contributions to the relaxation of the free layer, associated with mode crossings of the SAF resonances and the free layer resonance. We have investigated the CAREER: Magnetization Dynamics and Damping in Magnetic Nanostructures Tim Mewes, University of Alabama Tuscaloosa, DMR 0952929 FMR mode positions as a function of excitation frequency. red: free layer resonance, blue: SAF resonances. For the free layer the linewidth is shown on the right for two different field orientations with respect to the bias field. Frequency dependence of the FMR linewidth of iron oxide nanoparticles in an aqueous solution. The nanoparticles have a core of approximately 12 nanometers in diameter and are coated with polyacrylic acid of different TEM images of flower- shaped magnetic nanoparticles. 0 2 4 6 8 10 0 10 20 30 40 parallel- free layer parallel- low -field m ode parallel- high-field m ode antiparallel- low -field m ode f[G Hz] H [kO e] 0 200 400 600 H [kA/m ] 0 50 100 150 200 250 300 0 10 20 30 40 fre e layer - para llel fre e layer - antip ara llel H [Oe] f[G Hz] 0 5 10 15 20 25 30 35 40 45 600 700 800 900 1000 1100 L in ew id th, 15 K co atin g L in ew id th, 5K coating L in ew id th, 10 0 K coa ting H [O e] f[G Hz] 50 60 70 80 H [kA/m ]
CAREER: Magnetization Dynamics and Damping
Feb 02, 2016
CAREER: Magnetization Dynamics and Damping in Magnetic Nanostructures Tim Mewes, University of Alabama Tuscaloosa, DMR 0952929. This Faculty Early CAREER award funds research to investigate the magnetization dynamics and damping of magnetic nanostructures. - PowerPoint PPT Presentation
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This Faculty Early CAREER award funds research to investigate the magnetization dynamics and damping of magnetic nanostructures. We have extended our broadband ferromagnetic resonance capabilities to enable parallel pumping experiments. We have investigated the relaxation in synthetic antiferromagnet (SAF) systems in proximity to a free layer. This has resulted in the discovery of additional unidirectional resonant contributions to the relaxation of the free layer, associated with mode crossings of the SAF resonances and the free layer resonance.We have investigated the magnetization dynamics of magnetic nanoparticles of different shapes and sizes in different solutions.
CAREER: Magnetization Dynamics and Damping in Magnetic Nanostructures
Tim Mewes, University of Alabama Tuscaloosa, DMR 0952929
FMR mode positions as a function of excitation frequency. red: free layer resonance, blue: SAF resonances. For the free layer the linewidth is shown on the right for two different field orientations with respect to the bias field.
Frequency dependence of the FMR linewidth of iron oxide nanoparticles in an aqueous solution. The nanoparticles have a core of approximately 12 nanometers in diameter and are coated with polyacrylic acid of different molecular weights.
TEM images of flower-shaped magnetic nanoparticles.
0 2 4 6 8 100
10
20
30
40 parallel - free layer parallel - low-field mode parallel - high-field mode antiparallel - low-field mode
f [G
Hz]
H [kOe]
0 200 400 600 H [kA/m]
0 50 100 150 200 250 3000
10
20
30
40
free layer - parallel free layer - antiparallel
H [Oe]
f [G
Hz]
0 5 10 15 20 25 30 35 40 45
600
700
800
900
1000
1100
Linewidth, 15K coating Linewidth, 5K coating Linewidth, 100K coating
H [O
e]
f [GHz]
50
60
70
80
H [k
A/m
]
Undergraduate student Camille Brandenburg from the University of Maryland Eastern Shore (UMES) worked as a summer student on broadband FMR measurements of magnetic nanoparticles.
In addition to Behrouz Khodadadi, the graduate student supported by this grant, currently Chayada Surawanitkun, a graduate student from Khon Kaen University in Thailand, is visiting us for six months; a joint manuscript has been accepted for publication.
We have also reached out to a local Elementary School performing demonstrations thereby enhancing the children's science education.
CAREER: Magnetization Dynamics and Damping in Magnetic Nanostructures
Tim Mewes, University of Alabama Tuscaloosa, DMR 09529299
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