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Magnonic band structure investigation of one-dimensional bi-component magnonic crystal waveguides.

Ma FS, Lim HS, Zhang VL, Ng SC, Kuok MH - Nanoscale Res Lett (2012)

Bottom Line: Our results show that the widths and center frequencies of the bandgaps are controllable by the component materials, the stripe widths, and the orientation of the applied magnetic field.One salient feature of the bandgap frequency plot against stripe width is that there are n-1 zero-width gaps for the nth bandgap for both transversely and longitudinally magnetized waveguides.Additionally, the largest bandgap widths are primarily dependent on the exchange constant contrast between the component materials of the nanostructured waveguides.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, National University of Singapore, Singapore, 117542, Singapore. phylimhs@nus.edu.sg.

ABSTRACT
The magnonic band structures for exchange spin waves propagating in one-dimensional magnonic crystal waveguides of different material combinations are investigated using micromagnetic simulations. The waveguides are periodic arrays of alternating nanostripes of different ferromagnetic materials. Our results show that the widths and center frequencies of the bandgaps are controllable by the component materials, the stripe widths, and the orientation of the applied magnetic field. One salient feature of the bandgap frequency plot against stripe width is that there are n-1 zero-width gaps for the nth bandgap for both transversely and longitudinally magnetized waveguides. Additionally, the largest bandgap widths are primarily dependent on the exchange constant contrast between the component materials of the nanostructured waveguides.

No MeSH data available.


Dispersion relations for longitudinally magnetized MCWs. (a) 16Fe/4Ni, (b) 16Fe/4Py, (c) 16Py/4Ni, (d) 16Co/4Ni, (e) 16Co/4Py, and (f) 16Co/4Fe MCWs under a H = 600 mT field. The dotted lines indicate the Brillouin zone boundaries q = nπ/a, and the first, second, and third bandgaps are denoted by the red-, green-, and blue-shaded regions, respectively. The intensities of the SWs are represented by color scale.
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Figure 4: Dispersion relations for longitudinally magnetized MCWs. (a) 16Fe/4Ni, (b) 16Fe/4Py, (c) 16Py/4Ni, (d) 16Co/4Ni, (e) 16Co/4Py, and (f) 16Co/4Fe MCWs under a H = 600 mT field. The dotted lines indicate the Brillouin zone boundaries q = nπ/a, and the first, second, and third bandgaps are denoted by the red-, green-, and blue-shaded regions, respectively. The intensities of the SWs are represented by color scale.

Mentions: For the longitudinally magnetized waveguides (see Figure 1b), the calculated SW dispersion curves along the longitudinal symmetry axis of 16Fe/4Ni, 16Fe/4Py, 16Py/4Ni 16Co/4Ni, 16Co/4Py, and 16Co/4Fe MCWs for H = 600 mT are shown in Figure 4. Due to the effect of width confinement [22-24], the dispersion curves are characterized by a lower frequency limit, viz. 25.0 GHz for 16Fe/4Ni, 28.5 GHz for 16Fe/4Py, 21.5 GHz for 16Py/4Ni, 21.5 GHz for 16Co/4Ni, 25.0 GHz for 16Co/4Py, and 27.0 GHz for 16Co/4Fe MCWs. These values correspond to the minimum frequency of the lowest allowable SW modes propagating through the respective waveguides. Similar to the transverse case, the characteristics of bandgaps are also dependent on the component materials of the MCWs. For the 16Fe/4Ni MCW, the first three bandgaps with respective widths of 10.5, 39.0, and 61.5 GHz are shown in Figure 4a.


Magnonic band structure investigation of one-dimensional bi-component magnonic crystal waveguides.

Ma FS, Lim HS, Zhang VL, Ng SC, Kuok MH - Nanoscale Res Lett (2012)

Dispersion relations for longitudinally magnetized MCWs. (a) 16Fe/4Ni, (b) 16Fe/4Py, (c) 16Py/4Ni, (d) 16Co/4Ni, (e) 16Co/4Py, and (f) 16Co/4Fe MCWs under a H = 600 mT field. The dotted lines indicate the Brillouin zone boundaries q = nπ/a, and the first, second, and third bandgaps are denoted by the red-, green-, and blue-shaded regions, respectively. The intensities of the SWs are represented by color scale.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3475054&req=5

Figure 4: Dispersion relations for longitudinally magnetized MCWs. (a) 16Fe/4Ni, (b) 16Fe/4Py, (c) 16Py/4Ni, (d) 16Co/4Ni, (e) 16Co/4Py, and (f) 16Co/4Fe MCWs under a H = 600 mT field. The dotted lines indicate the Brillouin zone boundaries q = nπ/a, and the first, second, and third bandgaps are denoted by the red-, green-, and blue-shaded regions, respectively. The intensities of the SWs are represented by color scale.
Mentions: For the longitudinally magnetized waveguides (see Figure 1b), the calculated SW dispersion curves along the longitudinal symmetry axis of 16Fe/4Ni, 16Fe/4Py, 16Py/4Ni 16Co/4Ni, 16Co/4Py, and 16Co/4Fe MCWs for H = 600 mT are shown in Figure 4. Due to the effect of width confinement [22-24], the dispersion curves are characterized by a lower frequency limit, viz. 25.0 GHz for 16Fe/4Ni, 28.5 GHz for 16Fe/4Py, 21.5 GHz for 16Py/4Ni, 21.5 GHz for 16Co/4Ni, 25.0 GHz for 16Co/4Py, and 27.0 GHz for 16Co/4Fe MCWs. These values correspond to the minimum frequency of the lowest allowable SW modes propagating through the respective waveguides. Similar to the transverse case, the characteristics of bandgaps are also dependent on the component materials of the MCWs. For the 16Fe/4Ni MCW, the first three bandgaps with respective widths of 10.5, 39.0, and 61.5 GHz are shown in Figure 4a.

Bottom Line: Our results show that the widths and center frequencies of the bandgaps are controllable by the component materials, the stripe widths, and the orientation of the applied magnetic field.One salient feature of the bandgap frequency plot against stripe width is that there are n-1 zero-width gaps for the nth bandgap for both transversely and longitudinally magnetized waveguides.Additionally, the largest bandgap widths are primarily dependent on the exchange constant contrast between the component materials of the nanostructured waveguides.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, National University of Singapore, Singapore, 117542, Singapore. phylimhs@nus.edu.sg.

ABSTRACT
The magnonic band structures for exchange spin waves propagating in one-dimensional magnonic crystal waveguides of different material combinations are investigated using micromagnetic simulations. The waveguides are periodic arrays of alternating nanostripes of different ferromagnetic materials. Our results show that the widths and center frequencies of the bandgaps are controllable by the component materials, the stripe widths, and the orientation of the applied magnetic field. One salient feature of the bandgap frequency plot against stripe width is that there are n-1 zero-width gaps for the nth bandgap for both transversely and longitudinally magnetized waveguides. Additionally, the largest bandgap widths are primarily dependent on the exchange constant contrast between the component materials of the nanostructured waveguides.

No MeSH data available.