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Article Dans Une Revue Physical Review B: Condensed Matter and Materials Physics (1998-2015) Année : 2007

Diamagnetism of doped two-leg ladders and probing the nature of their commensurate phases

Résumé

We study the magnetic orbital effect of a doped two-leg ladder in the presence of a magnetic field component perpendicular to the ladder plane. Combining both low-energy approach (bosonization) and numerical simulations (density-matrix renormalization group) on the strong coupling limit (t-J model), a rich phase diagram is established as a function of hole doping and magnetic flux. Above a critical flux, the spin gap is destroyed and a Luttinger liquid phase is stabilized. Above a second critical flux, a reentrance of the spin gap at high magnetic flux is found. Interestingly, the phase transitions are associated with a change of sign of the orbital susceptibility. Focusing on the small magnetic field regime, the spin-gapped superconducting phase is robust but immediately acquires algebraic transverse (i.e. along rungs) current correlations which are commensurate with the 4k_F density correlations. In addition, we have computed the zero-field orbital susceptibility for a large range of doping and interactions ratio J/t : we found strong anomalies only in the vicinity of the commensurate fillings $\delta = 1/4$ and 1/2 and low J/t. However, the behavior of the orbital susceptibility reveals that the nature of these insulating phases is different: while for $\delta = 1/4$ a 4k_F charge density wave is confirmed, the $\delta = 1/2$ phase is shown to be a bond order wave.

Dates et versions

hal-00166732 , version 1 (09-08-2007)

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Guillaume Roux, Edmond Orignac, S. R. White, Didier Poilblanc. Diamagnetism of doped two-leg ladders and probing the nature of their commensurate phases. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2007, 76, pp.195105. ⟨10.1103/PhysRevB.76.195105⟩. ⟨hal-00166732⟩
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