@article { ISI:000274998200030,
	title = {Layered superconductors as negative-refractive-index metamaterials},
	journal = {PHYSICAL REVIEW B},
	volume = {81},
	number = {7},
	year = {2010},
	month = {FEB},
	publisher = {AMER PHYSICAL SOC},
	type = {Article},
	address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
	abstract = {We analyze the use of layered superconductors as strongly anisotropic metamaterials, which can possess negative-refractive-index in a wide frequency range. Superconductors are of particular interest because they have the potential to support low losses, which is critical for applications such as super-resolution imaging. We show that low-T(c) (s-wave) superconductors can be used to construct layered heterostructures with low losses for T \&lt;\&lt; T(c). However, the real part of their in-plane effective permittivity is very large, making coupling into the structure difficult. Moreover, even at low temperatures, layered high-T(c) superconductors have a large in-plane normal conductivity, producing large losses (due to d-wave symmetry). Therefore, it is difficult to enhance the evanescent modes in either low-T(c) or high-T(c) superconductors.},
	issn = {1098-0121},
	doi = {10.1103/PhysRevB.81.075101},
	author = {Rakhmanov, A. L. and Yampol{\textquoteright}skii, V. A. and Fan, J. A. and Federico Capasso and Nori, Franco}
}
