This Faculty Early CAREER award funds research to investigate the magnetization dynamics and damping of magnetic nanostructures. Our work on additional unidirectional resonant contributions to the relaxation, associated with mode crossings of the synthetic antiferro-magnet (SAF) resonances and the free layer resonance, has been published.We have investigated spin torque switching, comparing analytical, macro-spin and full micromagnetic solutions. We have extended our experimental capabilities by adding a magneto-optical Kerr effect setup and by implementing fully automated in-plane and elevation angle dependent broad-band FMR measurements. These new capabilities have been used to characterize Co2Mn0.4Fe0.6Si and other thin films.

CAREER: Magnetization Dynamics and Damping in Magnetic Nanostructures

Tim Mewes, University of Alabama Tuscaloosa , DMR 0952929

FMR linewidth of the free-layer resonance for different orientations of the external magnetic field with respect to the exchange bias direction of the SAF. The peaks in the linewidth are caused by mode crossings. APL 100, 032402 (2012).

Switching energy for spin torque switching as a function of the normalized current .

In-plane angular dependence for a Co2Mn0.4Fe0.6Si 30nm thin film of a) the ferromagnetic resonance field measured at 30GHz (similar data can be obtained at any frequency up to 55 GHz) and b) the magnetization reversal measured using our magnetooptical Kerr effect setup.

5800

5840

5880

59200

30

60

90

120

150

180

210

240

270

300

330

5800

5840

5880

5920

Hre

s [O

e] 30 GHz

a)b)

5 10 15 20 25 30 35 400

50

100

150

200

250 free layer - parallel free layer - antiparallel

H [O

e]

f [GHz]

0

5

10

15

20

H [k

A/m

]

Prof. Mark Williams from the University of Maryland Eastern Shore worked with us during the summer on micromagnetic simulations that included the Oersted field created by the currents in magnetic nanostructures.In addition to Behrouz Khodadadi, the graduate student supported by this grant, Chayada Surawanitkun, a graduate student from Khon Kaen University in Thailand, visited us for six months; one joint article has been published and another article has been accepted for publication.During summer 2012 Frank Heussner, an undergraduate student from the University of Kaiserslautern, worked with us on investigations of Co2Mn0.4Fe0.6Si thin films using our magnetooptical Kerr effect and ferromagnetic resonance capabilities. The work has been submitted as a contribution to the 2013 Intermag/MMM conference.

CAREER: Magnetization Dynamics and Damping in Magnetic Nanostructures

Tim Mewes, University of Alabama Tuscaloosa , DMR 095292

During summer 2012 the PI organized a High School summer program and a summer internship program for the MINT Center. These programs brought 8 local High School students and 7 international students to the MINT Center to work for nine weeks with faculty mentors.