H. J. A. Molegraaf

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Quantum criticality is associated with a system composed of a nearly infinite number of interacting quantum degrees of freedom at zero temperature, and it implies that the system looks on average the same regardless of the time- and length scale on which it is observed. Electrons on the atomic scale do not exhibit such symmetry, which can only be generated(More)
Optical data are reported on a spectral weight transfer over a broad frequency range of Bi2Sr2CaCu2O8+delta, when this material became superconducting. Using spectroscopic ellipsometry, we observed the removal of a small amount of spectral weight in a broad frequency band from 10(4) cm(-1) to at least 2 x 10(4) cm(-1), due to the onset of superconductivity.(More)
In strongly correlated systems the electronic properties at the Fermi energy (E(F)) are intertwined with those at high-energy scales. One of the pivotal challenges in the field of high-temperature superconductivity (HTSC) is to understand whether and how the high-energy scale physics associated with Mott-like excitations (|E-E(F)|>1 eV) is involved in the(More)
We present the ab-plane optical conductivity of four single crystals of Bi 2 Sr 2 CaCu 2 O 8+␦ ͑Bi2212͒ with different carrier doping levels from the strongly underdoped to the strongly overdoped range with T c = 66, 88, 77, and 67 K, respectively. We focus on the redistribution of the low frequency optical spectral weight ͑SW͒ in the superconducting and(More)
The c-axis optical properties of cuprate superconductors have been studied by grazing angle reeectivity technique. We tested the interlayer tunnelling (ILT) model of high temperature superconductivity and showed that the basic relation between the condensation energy of the superconducting state and the interlayer Josephson coupling does not hold for Tl 2(More)
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