02182nas a2200301   4500008004500000020001400045245011000059210006900169260000800238300000600246490000800252520133400260653002201594653001201616100001801628700001201646700001701658700001401675700001801689700001701707700001901724700002001743700002101763700001401784700001901798700001401817856004901831       2020                        Engldsh    a2469-995000aLinear dichroism infrared resonance in overdoped, underdoped, and optimally doped cuprate superconductors0 aLinear dichroism infrared resonance in overdoped underdoped and   cAug  a60 v1023 a<p>By measuring the polarization changes in terahertz, infrared, and visible radiation over an extended energy range (3-2330 meV), we observe symmetry breaking in cuprate high-temperature superconductors over wide energy, doping, and temperature ranges. We measure the polarization rotation (Re[theta(F)]) and ellipticity (Im[theta(F)]) of transmitted radiation through thin films as the sample is rotated. We observe a twofold rotational symmetry in theta(F), which is associated with linear dichroism (LD) and occurs when electromagnetic radiation polarized along one direction is absorbed more strongly than radiation polarized in the perpendicular direction. Such polarization anisotropies can be generally associated with symmetry breakings. We measure the amplitude of the LD signal and study its temperature, energy, and doping dependence. The LD signal shows a resonant behavior with a peak in the few hundred meV range, which is coincident with the midinfrared optical feature that has been associated with the formation of the pseudogap state. The strongest LD signal is found in underdoped films, although it is also observed in optimally and overdoped samples. The LD signal is consistent with an electronic nematic order which is decoupled from the crystallographic axes as well as novel magnetoelectric effects.</p>10aMaterials Science10aPhysics1 aMukherjee, A.1 aSeo, J.1 aArik, M., M.1 aZhang, H.1 aZhang, C., C.1 aKirzhner, T.1 aGeorge, D., K.1 aMarkelz, A., G.1 aArmitage, N., P.1 aKoren, G.1 aWei, J., Y. T.1 aCerne, J.  uhttps://markelz.physics.buffalo.edu/node/238