Search results

Sort By:

Limit search:

The t-J Model in a Strong Magnetic Field

100%

Sherman A.

The normal-state energy spectrum of the two-dimensional t-J model in a homogeneous perpendicular magnetic field B is investigated using the Mori projection operator technique. The density of states at the Fermi level as a function of 1/B reveals both high- and low-frequency oscillations. The high-frequency oscillations correspond to large Fermi surfaces, while the low-frequency components are related to van Hove singularities in the Landau subbands, which stem from their bending due to strong electron correlations. Frequencies of the low-frequency components are of the same order of magnitude as those observed in underdoped cuprates. These components become dominant if smoothing processes are involved. It is shown that despite increased distances between subbands the pseudogap affects only slightly the frequency of density of states oscillations.

Magnetic Properties of the Spin-1 Two-Dimensional J_{1}-J_{3} Heisenberg Model on a Triangular Lattice

51%

Rubin P., Sherman A., Schreiber M.

Acta Physica Polonica A

2014

vol. 126

issue 1

242-243

Motivated by the recent experiment in NiGa_{2}S_{4}, the spin-1 Heisenberg model on a triangular lattice with the ferromagnetic nearest- and antiferromagnetic third-nearest-neighbor exchange interactions, J_{1} = -(1 - p)J and J_{3} = pJ, J > 0, is studied in the range of the parameter 0 ≤ p ≤ 1. Mori's projection operator technique is used as a method, which retains the rotation symmetry of spin components and does not anticipate any magnetic ordering. For zero temperature several phase transitions are observed. At p ≈ 0.2 the ground state is transformed from the ferromagnetic order into a disordered state, which in its turn is changed to an antiferromagnetic long-range ordered state with the incommensurate ordering vector Q' ≈ (1.16, 0) at p ≈0.31. With growing p the ordering vector moves along the line Q'-Q_{c} to the commensurate point Q_{c} = (2π/3, 0), which is reached at p = 1. The final state with the antiferromagnetic long-range order can be conceived as four interpenetrating sublattices with the 120° spin structure on each of them. Obtained results offer a satisfactory explanation for the experimental data in NiGa_{2}S_{4}.

Refine search results

2 Acta Physica Polonica A

1 2015

1 2014

2 Sherman A.

1 Rubin P.

1 Schreiber M.

Search results

The t-J Model in a Strong Magnetic Field

Magnetic Properties of the Spin-1 Two-Dimensional J_{1}-J_{3} Heisenberg Model on a Triangular Lattice