Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2009-02-15
Eur. Phys. J. B 68, 59-66 (2009)
Physics
Condensed Matter
Strongly Correlated Electrons
8 pages, 6 figures, Accepted to EPJB
Scientific paper
10.1140/epjb/e2009-00077-7
The ground-state magnetic phase diagram of a spin $S=1/2$ two-leg ladder with alternating rung exchange $J_{\perp}(n)=J_{\perp}[1 + (-1)^{n} \delta]$ is studied using the analytical and numerical approaches. In the limit where the rung exchange is dominant, we have mapped the model onto the effective quantum sine-Gordon model with topological term and identified two quantum phase transitions at magnetization equal to the half of saturation value from a gapped to the gapless regime. These quantum transitions belong to the universality class of the commensurate-incommensurate phase transition. We have also shown that the magnetization curve of the system exhibits a plateau at magnetization equal to the half of the saturation value. We also present a detailed numerical analysis of the low energy excitation spectrum and the ground state magnetic phase diagram of the ladder with rung-exchange alternation using Lanczos method of numerical diagonalizations for ladders with number of sites up to N=28. We have calculated numerically the magnetic field dependence of the low-energy excitation spectrum, magnetization and the on-rung spin-spin correlation function. We have also calculated the width of the magnetization plateau and show that it scales as $\delta^{\nu}$, where critical exponent varies from $\nu =0.87\pm0.01$ in the case of a ladder with isotropic antiferromagnetic legs to $\nu =1.82\pm0.01 $ in the case of ladder with ferromagnetic legs. Obtained numerical results are in an complete agreement with estimations made within the continuum-limit approach.
Japaridze George I.
Mahdavifar Saeed
No associations
LandOfFree
Magnetic phase diagram of the dimerized spin $S=1/2$ ladder does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Magnetic phase diagram of the dimerized spin $S=1/2$ ladder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic phase diagram of the dimerized spin $S=1/2$ ladder will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-718196