Intrinsic left-handed electromagnetic properties in anisotropic superconductors

摘要

Left-handed materials usually are realized in artificial subwavelength structures. Here, we show that some anisotropic superconductors such as Bİ_2Sr_2CaCu_2O_(8+δ), YBa2Cu_xO_y, and La_(2-x)Sr_xCuO_4, are intrinsic left-handed materials. The condition is that the plasma frequency in the c axis, ω_C, and in the ab plane, ω_(ab), and the operating angular frequency, ω, satisfy ω_c< ω_(ab) . In addition, ω should be smaller than the superconducting energy gap to sustain superconductivity. We study the reflection and transmission of electromagnetic waves and reveal negative refraction and the backward wave with the phase velocity opposite to the direction of energy flux propagation. We also discuss possible approaches for improvement, making these properties feasible for experimental validation. Being intrinsic left-hand materials, the anisotropic superconductors are promising for applications in functional electromagnetic devices in the terahertz frequency band.