Experimental Design for Free Space Nonlinear Magnetic Material Characterization Using Photonic Structures

2008 ◽  
Vol 1118 ◽  
Author(s):  
Eric Kuster ◽  
Ricky L. Moore
Keyword(s):  
Magnetic Field ◽  
Experimental Design ◽  
Power Density ◽  
Free Space ◽  
Particulate Composites ◽  
Photonic Structure ◽  
Critical Fields ◽  
Pump Frequency ◽  
Photonic Structures ◽  
Field Localization

ABSTRACTMeasuring nonlinear AC dielectric or magnetic properties of ferro and ferri magnetic materials has often required large, extremely high power and bulky equipment configurations for production of the required intense electric and/or magnetic fields. Multiple RF cavities, striplines or waveguide test fixtures may be required. The techniques often require 10s of cubic millimeter too centimeter material volumes. This paper presents results from an initial experimental design of a free space based measurement configuration for small material volumes such as nano and micro particulates or particulate composites. The technique uses wideband radiators and modest variable power radio frequency pumping sources. A second design uses, in concert with a higher power pump, a variable frequency low power probe source at frequencies other than that of the pump. A two dimensional photonic bandgap (PBG) structure is common to both configurations. The photonic structure acts to enhance power density at frequencies associated with localized electromagnetic fields constrained to small volumes of the photonic structures. Field localization is recognized and has been applied in biological diagnostics and treatment [Phys. Rev. v109, 1492; Phys. Rev. B, v55 and 62, n. 19 and 16, pp 13234 and 11230 and Chem.Soc.News, 1998, v27, p241].Modeling of various measurement configurations is based upon expansion of incident and propagating fields in characteristic modes external and within the structure. A proper choice of photonic structure, material and pump frequency is found to localize fields in air, between the structural dielectric members of the photonic structure. This will allow small magnetic or electric samples to be inserted for exposure in these regions. The electromagnetic reflection, transmission, absorption and field/power density multiplier of the photonic structure can be measured at multiple frequencies and reflect the dielectric or magnetic nonlinearity and changed dispersion induced at the pump frequency. One PBG-free space combination will be presented that finds power density multipliers of 10 6. Thus a 10 watt pump source will produce RF magnetic field strengths near 10 Oe. This magnetic field should be sufficient to exceed critical fields for many ferri and ferromagnetic samples inserted in the volume of field localization.

scholarly journals Experimental signatures of nodeless multiband superconductivity in a $$\hbox {2H-Pd}_{0.08} \hbox {TaSe}_2$$ single crystal

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chanhee Kim ◽  
Dilip Bhoi ◽  
Yeahan Sur ◽  
Byung-Gu Jeon ◽  
Dirk Wulferding ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Crystal ◽  
Zero Magnetic Field ◽  
Anisotropy Ratio ◽  
Strong Temperature Dependence ◽  
Critical Fields ◽  
Band Theory ◽  
Plane Field ◽  
Low Field ◽  
Out Of Plane

AbstractIn order to understand the superconducting gap nature of a $$\hbox {2H-Pd}_{0.08} \hbox {TaSe}_2$$ 2H-Pd 0.08 TaSe 2 single crystal with $$T_{c} = 3.13 \text { K}$$ T c = 3.13 K , in-plane thermal conductivity $$\kappa $$ κ , in-plane London penetration depth $$\lambda _{\text {L}}$$ λ L , and the upper critical fields $$H_{c2}$$ H c 2 have been investigated. At zero magnetic field, it is found that no residual linear term $$\kappa _{0}/T$$ κ 0 / T exists and $$\lambda _{\text {L}}$$ λ L follows a power-law $$T^n$$ T n (T: temperature) with n = 2.66 at $$T \le \frac{1}{3}T_c$$ T ≤ 1 3 T c , supporting nodeless superconductivity. Moreover, the magnetic-field dependence of $$\kappa _{0}$$ κ 0 /T clearly shows a shoulder-like feature at a low field region. The temperature dependent $$H_{c2}$$ H c 2 curves for both in-plane and out-of-plane field directions exhibit clear upward curvatures near $$T_c$$ T c , consistent with the shape predicted by the two-band theory and the anisotropy ratio between the $$H_{c2}$$ H c 2 (T) curves exhibits strong temperature-dependence. All these results coherently suggest that $$\hbox {2H-Pd}_{0.08} \hbox {TaSe}_2$$ 2H-Pd 0.08 TaSe 2 is a nodeless, multiband superconductor.

INFLUENCE OF AN EXTERNAL MAGNETIC FIELD ON THE DYNAMICS OF A NEW-PHASE NUCLEUS IN THE VICINITY OF THE FIRST-ORDER PHASE TRANSITION IN MAGNETS WITH DEFECTS PRESENT

2012 ◽  
Vol 26 (28) ◽  
pp. 1250183 ◽  
Author(s):  
VLADIMIR NAZAROV ◽  
RISHAT SHAFEEV
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
External Magnetic Field ◽  
Magnetic Anisotropy ◽  
Spin Reorientation ◽  
Critical Fields ◽  
First Order ◽  
Phase Nucleus ◽  
First Order Phase Transition ◽  
New Phase

Theoretically, with the aid of a soliton model, the evolution of a new-phase nucleus near the first-order spin-reorientation phase transition in magnets has been investigated in an external magnetic field. The influence of an external field and one-dimensional defects of magnetic anisotropy on the dynamics of such nucleus has been demonstrated. The conditions for the localization of the new-phase nucleus in the region of the magnetic anisotropy defect and for its escape from the defect have been determined. The values of the critical fields which bring about the sample magnetization reversal have been identified and estimated.

Comparison of Magnetostrictive Performance Loss of Particulate Tb0.3 Dy0.7 Fe2 Epoxy Composites Prepared with Different Matrix Polymers M. Shanmugham et al.: Comparison of Magnetostrictive Performance Loss of Particulate Tb0.3 Dy0.7 Fe2 Epoxy Composites

2004 ◽  
Vol 19 (3) ◽  
pp. 795-805 ◽  
Author(s):  
Manikantan Shanmugham ◽  
Harold Bailey ◽  
William D. Armstrong
Keyword(s):  
Magnetic Field ◽  
Glass Transition ◽  
Matrix Material ◽  
Epoxy Composites ◽  
Particulate Composites ◽  
Specimen Preparation ◽  
Performance Loss ◽  
Magnetostrictive Strain ◽  
Relative Damage ◽  
Low Modulus

Particulate composites of magnetostrictive Terfenol-D were prepared with polyamine and anhydride cured epoxy polymer matrices with the presence or the absence of a strong magnetic field. These composites were studied to investigate (i) the influence of magnetic field that is applied during specimen preparation in strain output levels, (ii) performance loss at high temperatures, and (iii) the influence of matrix material in magnetostrictive strain performance. A six-way comparison is made of materials processed under magnetic field with materials processed under no magnetic field, and magnetostrictive strain performance at glass transition finish temperature with magnetostrictive strain performance at glass transition start temperature, and magnetostrictive strain performance in low modulus matrix systems with magnetostrictive strain performance in high modulus matrix systems. A four-way comparison is also made between the micrographs for strain-cycled and non-strain-cycled samples and relative damage incurred by samples prepared using high and low modulus matrix systems.

Evaluation of the Equivalent Lumped Element Parameters of Modified Microstrip Ring Resonator

2015 ◽  
Vol 735 ◽  
pp. 278-281
Author(s):  
Yi Lung Then ◽  
Kok Yeow You ◽  
Mohamad Ngasri Dimon ◽  
Wei Ying Lai
Keyword(s):  
Magnetic Field ◽  
Free Space ◽  
Ring Resonator ◽  
Element Model ◽  
Network Analyzer ◽  
Simulation Data ◽  
Lumped Element ◽  
Lumped Element Model ◽  
Microstrip Ring ◽  
Microstrip Ring Resonator

Microstrip ring resonator (MRR) sensor was modeled by simple equivalent lumped element circuits in free space based on simulation data obtained from Microwave Office (AWR) simulator and comparison was made with the measurements using the E5071C Network Analyzer. The calculated reflection coefficient, |G| and complex input impedanceZinusing lumped element model were compared with the measurements results. Both results showed well agreement with a little discrepancy, basically due to imperfect soldering. The MRR was designed to have operating frequencies between 0.5 GHz and 4.5 GHz. The maximum surrounding of magnetic field,Hϕis within 15 A/m in free space.

UPPER CRITICAL FIELD OF UNCONVENTIONAL SUPERCONDUCTORS FROM CHEMICAL EQUILIBRIUM

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3443-3448 ◽  
Author(s):  
A. KALLIO ◽  
J. HISSA ◽  
T. HÄYRYNEN ◽  
V. BRÄYSY
Keyword(s):  
Magnetic Field ◽  
Critical Field ◽  
Normal State ◽  
Chemical Equilibrium ◽  
Critical Density ◽  
Upper Critical Field ◽  
Universal Function ◽  
Zero Magnetic Field ◽  
Mathematical Treatment ◽  
Critical Fields

We have shown previously that many normal state properties of high Tc superconductors in zero magnetic field can be understood in terms of a single universal function f(t) in the scaled variable t=T/T*, where T* is connected with temperature independent gap 2Δ=2kBT*, which gives the binding energy of a pair in analogy with dissociation of molecules. The function f(t) determines the fraction of bosons (B++) and fermions (h+) at temperature T and it is obtained from the mathematical treatment of chemical equilibrium with respect to the reaction B++⇌ 2h+. Since for magnetic fields of reasonable strength the Zeeman energy is much smaller than the pseudo gap Δ~100K-800K, the function f(t) in the normal state is largely independent of magnetic field. The main effect of the magnetic field is to increase the tendency for bosons to localize. This means that the critical density nL for delocalization in the ab-plane direction and the critical density for superfluidity nc (≳ nL) both increase with magnetic field. This causes the corresponding temperatures TBL(H) and Tc(H) to go down with the field. Assuming a power law dependence nc(H)/nc(0)=1+AHμ, the upper critical fields for several heavy fermion compounds are shown to fall into a single curve. The purpose here is to show that the upper critical field Hc2(y) (y=Tc(H)/Tc(0)) can be expressed in a simple way in terms of f(t). We show that this theory predicts all the shapes of Hc2(y) observed in several unconventinal superconductors such as Tl 2 Ba 2 CuO 6+δ, with Tc=15 K.

Magnetic modulation of Fano resonances in optically thin terahertz superlattice metasurfaces

2021 ◽  
Author(s):  
Subhajit Karmakar ◽  
Ravi Varshney ◽  
Dibakar Roy Chowdhury
Keyword(s):  
Magnetic Field ◽  
Free Space ◽  
Skin Depth ◽  
Electromagnetic Energy ◽  
Magnetic Control ◽  
Fano Resonances ◽  
Electromagnetic Responses ◽  
On Chip ◽  
Magneto Resistance ◽  
Sub Wavelength

Abstract Optically thin metasurfaces operating at sub-skin depth thicknesses are intriguing because of its associated low plasmonic losses (compared to optically thick, beyond skin-depth metasurfaces). However, their applicability has been restricted largely because of reduced free space coupling with incident radiations resulting in limited electromagnetic responses. To overcome such limitations, we propose enhancement of effective responses (resonances) in sub-skin depth metasurfaces through incorporation of magneto-transport (Giant Magneto Resistance, GMR) concept. Here, we experimentally demonstrate dynamic magnetic modulation of structurally asymmetric metasurfaces (consisting of superlattice arrangement of thin (~ 10 nm each) magnetic (Ni)/ nonmagnetic (Al) layers) operating at terahertz (THz) domain. With increasing magnetic field (applied from 0 to 30 mT approximately, implies increasing superlattice conductivity), we observe stronger confinement of electromagnetic energy at the resonances (both in dipole and Fano modes). Therefore, this study introduces unique magnetically reconfigurable ability in Fano resonant THz metamaterials, which directly improves its performances operating in the sub-skin depth regime. Our study can be explained by spin-dependent terahertz magneto-transport phenomena in metals and can stimulate the paradigm for on-chip spin-based photonic technology enabling dynamic magnetic control over compact, sub-wavelength, sub-skin depth metadevices.

Eigenmodes in a photonic structure with a torsion-deformed nematic liquid crystal exposed to a magnetic field

2020 ◽  
Vol 102 (4) ◽  
Author(s):  
Vladimir A. Gunyakov ◽  
Alexander M. Parshin ◽  
Ivan V. Timofeev ◽  
Victor Ya. Zyryanov
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Photonic Structure

THE ADMITTANCE OF AN INFINITE CYLINDRICAL ANTENNA IN A LOSSY INCOMPRESSIBLE, ANISOTROPIC PLASMA

1967 ◽  
Vol 45 (12) ◽  
pp. 4019-4038 ◽  
Author(s):  
Edmund K. Miller
Keyword(s):  
Magnetic Field ◽  
Free Space ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Floating Potential ◽  
Space Layer ◽  
Cylindrical Antenna ◽  
Warm Plasma ◽  
Positive Ion ◽  
Uniform Plasma

A numerical investigation of the admittance of an infinite, circular cylindrical antenna excited at a circumferential gap of nonzero thickness, and immersed in a lossy incompressible magnetoplasma with the antenna parallel to the static magnetic field is described. A concentric free-space layer (the vacuum sheath) which separates the antenna from the external uniform plasma is included in the analysis to approximate the positive ion sheath which may form about a body at floating potential in a warm plasma. The numerical results for the antenna admittance show that: (1) in the absence of a sheath, a sharp admittance maximum is found at the electron cyclotron frequency, with the maximum more pronounced when the plasma frequency exceeds the cyclotron frequency than for the converse case; (2) the vacuum sheath shifts upward in frequency and reduces in amplitude the admittance maximum which occurs for the sheathless case at the cyclotron frequency; (3) a kink or minimum in the admittance is found at the plasma frequency.

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