Precessional dynamics in microarrays of nanomagnets

Kruglyak, V. V.; Barman, Anjan; Hicken, R. J.; Childress, J. R.; Katine, J. A.

doi:10.1063/1.1849057

Cited by 32 publications

(29 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the nonuniform demagnetizing field may lead to the spatial confinement and quantization of spin-wave modes on the nanometer length scale. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] For thin-film elements where the magnetization lies in plane, the magnitude of the static in-plane demagnetizing field and the nonuniformity of the total effective field acting upon the magnetization increase when the element aspect ratio ͑size to thickness͒ is reduced. This results in a richer mode spectrum and hence in a less uniform magnetic response to a pulsed magnetic field, which can be directly imaged in the case of micrometer sized magnetic elements.…”

Section: Introductionmentioning

confidence: 99%

“…15 and 16 but have about five times greater total thickness, and hence are characterized by a greater nonuniformity of the static magnetization and the total effective field within the element. We found that the precessional mode spectra vary in a discontinuous and complicated fashion as the bias magnetic field is reduced.…”

Section: Introductionmentioning

confidence: 99%

“…33 In our previous study of 2.5-nm-thick square nanomagnets of less than 200 nm size, we observed a dynamical regime in which the response to a uniform pulsed magnetic field was dominated by nonuniform precessional modes localized near the edges perpendicular to the direction of the bias field. 15,16 Micromagnetic simulations of magnetization dynamics in thicker elements revealed the possible existence of a greater number of modes of a more complicated character, 19 and also suggested that the exact ground state of the magnetization in the nanoelements might be the key factor in determining their dynamical properties.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Time-resolved investigation of magnetization dynamics of arrays of nonellipsoidal nanomagnets with nonuniform ground states

et al. 2008

Self Cite

View full text Add to dashboard Cite

Time-resolved scanning Kerr microscopy measurements have been performed upon arrays of square ferromagnetic nanoelements of different sizes and for a range of bias fields. The experimental results were compared to micromagnetic simulations of model arrays in order to understand the nonuniform precessional dynamics within the elements. In the experimental spectra acquired from an element of length of 236 nm and thickness of 13.6 nm, two branches of excited modes were observed to coexist above a particular bias field. Below this so-called crossover field, the higher frequency branch was observed to vanish. Micromagnetic simulations and Fourier imaging revealed that modes from the higher frequency branch had large amplitude at the center of the element where the effective field was parallel to the bias field and the static magnetization. Modes from the lower frequency branch had large amplitude near the edges of the element perpendicular to the bias field. The simulations revealed significant canting of the static magnetization and effective field away from the direction of the bias field in the edge regions. For the smallest element sizes and/or at low bias field values, the effective field was found to become antiparallel to the static magnetization. The simulations revealed that the majority of the modes were delocalized with finite amplitude throughout the element while the spatial character of a mode was found to be correlated with the spatial variation in the total effective field and the static magnetization state. The simulations also revealed that the frequencies of the edge modes are strongly affected by the spatial distribution of the static magnetization state both within an element and within its nearest neighbors. Furthermore, the simulations suggest that collective modes may be supported in arrays of interacting nanomagnets, which act as magnonic crystals.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time-resolved investigation of magnetization dynamics of arrays of nonellipsoidal nanomagnets with nonuniform ground states

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although the spatial character of the magnetization dynamics in nanometer-sized elements cannot be directly studied by TRSKM, the lack of a spatial resolution can be circumvented by combining the measurement of the time domain response from arrays of nanomagnets with thorough micromagnetic modeling. [14][15][16] In this Brief Report, TRSKM measurements were used to investigate the magnetization dynamics near one end of a long rectangular ferromagnetic wire. By using the TRSKM as a submicrometer probe of the magnetization dynamics at different points on the wire, we recorded its time-and position-dependent responses to a pulsed magnetic field.…”

mentioning

confidence: 99%

“…The images of the dynamic magnetization acquired at fixed pump-probe time delays revealed irregular stripes lying perpendicular to the long axis of the wire. We interpret the stripe pattern in terms of a collective mode of the quasiperiodic system of ripple domains 17 14 To make pump-probe measurements, a transmission line structure with a 30 m track width and separation was deposited around the elements so that they experienced an out-of-plane pulsed magnetic field. The pulsed field had rise and decay times of about 70 ps and 2.2 ns, respectively, and a maxi-mum strength of about 0.9 mT and was uniform over the area of the sample to better than 1%.…”

mentioning

confidence: 99%

Imaging small-amplitude magnetization dynamics in a longitudinally magnetized microwire

et al. 2008

Self Cite

View full text Add to dashboard Cite

We have used time-resolved scanning Kerr microscopy to study spin waves in a magnetic microwire subjected to a bias magnetic field applied parallel to its long axis. The spin-wave spectra obtained from different points near one end of the wire reveal several normal modes. We found that modes of a higher frequency occupied regions located further from the end of the wire. This was interpreted in terms of the confinement of the spin-wave modes by a nonuniform demagnetizing field. Furthermore, at a particular distance from the end of the wire, two or more modes occupying different regions along the width of the wire were observed. This was interpreted in terms of the confinement of the spin-wave modes due to an asymmetric variation in the local angle between the static magnetization and the effective direction of the wave vector of the confined modes. Images of the dynamic magnetization that are acquired at fixed pump-probe time delays revealed stripes lying perpendicular to the long axis of the wire and, hence, to the applied magnetic field. We interpret the stripe pattern in terms of a collective mode of the quasiperiodic system of ripple domains existing within the polycrystalline sample. Our results give an additional insight into the connection between the nonuniform static magnetic state in small magnetic elements and their precessional dynamics, which is fundamentally important for the design of future high-speed switching and spin-wave logic devices of magnonics. The inherent nonuniformity of magnetization configurations in nonellipsoidal magnetic elements makes them the perfect objects for the investigation of wave phenomena in nonuniform media. The elementary excitations of magnetic media ͑so-called spin waves͒ have a strongly nonlinear dispersion, which is complicated by long-range magnetodipole interaction. In most magnetic elements of finite size, the latter remarkably makes the internal magnetic field nonuniform even when the magnetization configuration is almost uniform. The nonuniform internal field may lead to the spatial confinement of spin-wave modes 1,2 while the dephasing of the modes leads to a nonuniform magnetic response to a uniform pulsed magnetic field. [3][4][5][6][7] Apart from the fundamental interest, the studies of the magnetization dynamics in small magnetic elements are driven by the fast growing market of high-speed magnetic data storage devices. In particular, chips incorporating magnetic random access memory are now becoming available. 8 Time-resolved scanning Kerr microscopy ͑TRSKM͒ 3 has become one of the most widely used tools for imaging the spatial character of the magnetization dynamics within micrometer-sized magnetic disks, 3,6 stripes, 2,9 rectangles, 3,10 and squares. 4,5,7,11,12 Magnetization dynamics in micrometersized magnetic tunnel junctions were imaged in Ref. 13. Although the spatial character of the magnetization dynamics in nanometer-sized elements cannot be directly studied by TRSKM, the lack of a spatial resolution can be circumvented by combining the measur...

show abstract

Spin-Wave Dynamics in Ultra-thin Ferromagnetic Films, Patterned, and Non-patterned

Janardhanan,

Krawczyk,

Trzaskowska

2024

Nanostructure Science and Technology

View full text Add to dashboard Cite

Precessional dynamics in microarrays of nanomagnets

Cited by 32 publications

References 13 publications

Time-resolved investigation of magnetization dynamics of arrays of nonellipsoidal nanomagnets with nonuniform ground states

Time-resolved investigation of magnetization dynamics of arrays of nonellipsoidal nanomagnets with nonuniform ground states

Imaging small-amplitude magnetization dynamics in a longitudinally magnetized microwire

Spin-Wave Dynamics in Ultra-thin Ferromagnetic Films, Patterned, and Non-patterned

Contact Info

Product

Resources

About