Volume 93, Number 5, March 2011
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||11 March 2011|
A non-BCS mechanism for superconductivity in underdoped cuprates via attraction between spin vortices
Dipartimento di Fisica “G. Galilei”, INFN - I-35131 Padova, Italy, EU
2 College of Material Science and Optoelectronics Technology, Graduate University of Chinese Academy of Science Beijing 100049, China
3 Institute of Theoretical Physics, Chinese Academy of Sciences - Beijing 100190, China
4 Institute of Physics, Chinese Academy of Sciences - Beijing 100190, China
Accepted: 13 February 2011
We propose a non-BCS mechanism for superconductivity in hole-underdoped cuprates based on a gauge approach to the t-J model. The gluing force is an attraction between spin vortices centered on the empty sites of two opposite Néel sublattices, leading to pairing of charge carriers. In the presence of these pairs, a gauge force coming from the single occupancy constraint induces, in turn, the pairing of the spin carriers. The combination of the charge and spin pairs gives rise to a finite density of incoherent hole pairs, leading to a finite Nernst signal as precursor to superconductivity. The true superconducting transition occurs at an even lower temperature, via a 3D XY-type transition. The main features of this non-BCS description of superconductivity are consistent with the experimental results in underdoped cuprates, especially the contour plot of the Nernst signal.
PACS: 71.10.Hf – Non-Fermi-liquid ground states, electron phase diagrams and phase transitions in model systems / 11.15.-q – Gauge field theories / 71.27.+a – Strongly correlated electron systems; heavy fermions
© EPLA, 2011
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