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Three-dimensional magnetic cloak working from d.c. to 250 kHz.

Zhu J, Jiang W, Liu Y, Yin G, Yuan J, He S, Ma Y - Nat Commun (2015)

Bottom Line: In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields.Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz.The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310058, China.

ABSTRACT
Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.

No MeSH data available.


Related in: MedlinePlus

Schematic of the device.The bilayer structure consists of an inner SC shell (R1≤r<R2), shown in black, and an outer FM shell (R2≤r≤R3), shown in brown. The two identical halves of their components touch each other in the xy plane as indicated by the yellow dashed circle. The cloaked object (shown in yellow) is placed inside the cloaking region (r<R1), shown in white. In our measurement, the c axis of the YBCO's unit cell in the SC shell is defined along the z axis, and the ab lattice plane is parallel to the xy coordinate plane. In our experiment, we select R3=1.5 R2=15 mm, which leads to μFM=1.63.
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f1: Schematic of the device.The bilayer structure consists of an inner SC shell (R1≤r<R2), shown in black, and an outer FM shell (R2≤r≤R3), shown in brown. The two identical halves of their components touch each other in the xy plane as indicated by the yellow dashed circle. The cloaked object (shown in yellow) is placed inside the cloaking region (r<R1), shown in white. In our measurement, the c axis of the YBCO's unit cell in the SC shell is defined along the z axis, and the ab lattice plane is parallel to the xy coordinate plane. In our experiment, we select R3=1.5 R2=15 mm, which leads to μFM=1.63.

Mentions: Figure 1 provides a schematic of the bilayer structure consisting of the SC inner shell (black) and FM outer shell (brown) in a non-magnetic background. Each shell consists of two firmly connected identical halves touching each other in the xy plane. The SC shell (inner radius R1 and outer radius R2) was machined and etched from two YBCO single-crystal cylinders. In Cartesian coordinates, the z axis is defined along the c axis of the YBCO's unit cell and the xy plane is parallel with the ab lattice plane. In this manner, the maximum applicable magnetic field is different along the z axis than a direction in the xy plane due to the material anisotropy41. The FM shell of outer radius R3 is a composite of NiZn soft ferrite powders and paraffin matrix by a proper weight ratio. The fabrication details can be found in the Methods section. Assuming a uniform static external field and a perfect SC shell (skin depth or London penetration depth is in the sub-micron scale41), the FM component required by an ideal 3D magnetic cloak should have a permeability of (see ref. 23 and also Supplementary Note 1)


Three-dimensional magnetic cloak working from d.c. to 250 kHz.

Zhu J, Jiang W, Liu Y, Yin G, Yuan J, He S, Ma Y - Nat Commun (2015)

Schematic of the device.The bilayer structure consists of an inner SC shell (R1≤r<R2), shown in black, and an outer FM shell (R2≤r≤R3), shown in brown. The two identical halves of their components touch each other in the xy plane as indicated by the yellow dashed circle. The cloaked object (shown in yellow) is placed inside the cloaking region (r<R1), shown in white. In our measurement, the c axis of the YBCO's unit cell in the SC shell is defined along the z axis, and the ab lattice plane is parallel to the xy coordinate plane. In our experiment, we select R3=1.5 R2=15 mm, which leads to μFM=1.63.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696515&req=5

f1: Schematic of the device.The bilayer structure consists of an inner SC shell (R1≤r<R2), shown in black, and an outer FM shell (R2≤r≤R3), shown in brown. The two identical halves of their components touch each other in the xy plane as indicated by the yellow dashed circle. The cloaked object (shown in yellow) is placed inside the cloaking region (r<R1), shown in white. In our measurement, the c axis of the YBCO's unit cell in the SC shell is defined along the z axis, and the ab lattice plane is parallel to the xy coordinate plane. In our experiment, we select R3=1.5 R2=15 mm, which leads to μFM=1.63.
Mentions: Figure 1 provides a schematic of the bilayer structure consisting of the SC inner shell (black) and FM outer shell (brown) in a non-magnetic background. Each shell consists of two firmly connected identical halves touching each other in the xy plane. The SC shell (inner radius R1 and outer radius R2) was machined and etched from two YBCO single-crystal cylinders. In Cartesian coordinates, the z axis is defined along the c axis of the YBCO's unit cell and the xy plane is parallel with the ab lattice plane. In this manner, the maximum applicable magnetic field is different along the z axis than a direction in the xy plane due to the material anisotropy41. The FM shell of outer radius R3 is a composite of NiZn soft ferrite powders and paraffin matrix by a proper weight ratio. The fabrication details can be found in the Methods section. Assuming a uniform static external field and a perfect SC shell (skin depth or London penetration depth is in the sub-micron scale41), the FM component required by an ideal 3D magnetic cloak should have a permeability of (see ref. 23 and also Supplementary Note 1)

Bottom Line: In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields.Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz.The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310058, China.

ABSTRACT
Invisible cloaking is one of the major outcomes of the metamaterial research, but the practical potential, in particular for high frequencies (for example, microwave to visible light), is fatally challenged by the complex material properties they usually demand. On the other hand, it will be advantageous and also technologically instrumental to design cloaking devices for applications at low frequencies where electromagnetic components are favourably uncoupled. In this work, we vastly develop the bilayer approach to create a three-dimensional magnetic cloak able to work in both static and dynamic fields. Under the quasi-static approximation, we demonstrate a perfect magnetic cloaking device with a large frequency band from 0 to 250 kHz. The practical potential of our device is experimentally verified by using a commercial metal detector, which may lead us to having a real cloaking application where the dynamic magnetic field can be manipulated in desired ways.

No MeSH data available.


Related in: MedlinePlus