Hard magnetic properties of Mn-Ga melt-spun ribbons J. Appl. Phys. 112, 083901 (2012) Influence of chemical pressure in Sn-substituted Ni2MnGa Heusler alloy: Experimental and theoretical studies J. Appl. Phys. 112, 073921 (2012) Hysteresis effects in the inverse magnetocaloric effect in martensitic Ni-Mn-In and Ni-Mn-Sn J. Appl. Phys. 112, 073914 (2012) Magnetic and electronic properties of Fe and Ni codoped SnO2

Complex permeability spectra of Permalloy granular composite materials have been studied in the microwave frequency range. The heat-treated Permalloy particles in the air at several hundreds of °C have a high surface electrical resistance; the eddy current effect in the high frequency permeability spectra can be suppressed in the composite structure containing the percolated particles. A negative permeability has been obtained above 5GHz due to the natural magnetic resonance in the 70vol% particle content composite material. In this content, electrical permittivity spectra show a nonmetallic characteristic. This permeability dispersion can be applied for the left-handed media.

Tunable radio-frequency negative permittivity in nickel-alumina "natural" meta-composites Appl. Phys. Lett.Negative permittivity and permeability spectra of Cu/yttrium iron garnet hybrid granular composite materials in the microwave frequency range Appl. Phys. Lett. 103, 261906 (2013); 10.1063/1.4858976Frequency dependence of effective permittivity of carbon nanotube composites

The relative complex permittivity and permeability spectra of the coagulated copper and yttrium iron garnet (Cu/YIG) hybrid granular composite materials have been studied in the microwave range. The insulator to metal transition was observed at the percolation threshold of Cu particle content (φCu = 16.0 vol. %) in the electrical conductivity. In the percolation threshold, the low frequency plasmonic state caused by the metallic Cu particle networks was observed. The percolated Cu/YIG granular composites show simultaneous negative permittivity and permeability spectra under external magnetic fields.

Electromagnetic properties of hybrid composite materials containing copper and permalloy (Fe53Ni47 alloy) particles have been investigated in the RF to microwave frequency range up to 20 GHz. Double negative permittivity and permeability spectra have been observed in the percolated state of the hybrid composite material. The negative permittivity spectra in this composite can be attributed to the low frequency plasmonic state produced by the percolated Cu and permalloy cluster chains as well as the dielectric resonance of the isolated metal clusters. The refractive index spectra which were calculated from the measured permittivity and permeability data indicated the negative refraction from 200 MHz to 1.8 GHz. The near zero or zero refractive index state can be obtained near the two zero crossing frequencies in the refractive index spectra.