Study of Competing Charge, Spin and Superconducting Orders In Underdoped High-Temperature Superconductors.
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Date
2018-03-02
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Addis Ababa University
Abstract
Superconductivity often emerges in the proximity of, or in competition with,
symmetry-breaking ground states such as antiferromagnetism or charge den-
sity waves(CDW). A number of materials in the cuprate family, which includes
the high transition-temperature(high-Tc) superconductors, show spin and charge
density wave order. Thus a fundamental question is to what extent do these or-
dered states exist for compositions close to optimal for superconductivity. Recent
observations of CDWorder in Y Ba2Cu3Oy and other cuprate families have raised
interesting questions regarding the general role of charge modulations and the
relation to superconductivity. It was studied that in the system La2xBaxCuO4
SDW and CDW orders appear to be intertwined with a spatially-modulated
superconductivity. Here by developing a model Hamiltonian and by using quan-
tum _eld theory Green's function formalism, we obtain mathematical expres-
sions for superconductivity order parameter(_), and charge density wave order
parameter(W) in under-doped Y Ba2Cu3Oy. We plot the phase diagram of su-
perconducting order parameter (_) against temperature(T) for di_erent values
of charge density wave orders(W) in under-doped Y Ba2Cu3Oy. The relation-
ship between superconductivity(_), charge density wave(W), and spin density
wave(M) orders and their critical temperatures is studied theoretically for the
under-doped La2xBaxCuO4 superconductor and plot the phase diagrams of su-
perconducting order parameter(_) against temperature(T) for di_erent values of
charge density wave(W) and spin density wave(M) orders. Finally, we examine
the physics of combined mechanisms for cuprates and pnictides.
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Keywords
Study of Competing Charge, High-Temperature Superconductors, Superconducting State, Zero Resistance