Chen, X., Farhoodfar, A., McIntosh, T., Gooding, R. J., Leung, P. W.
A simple and commonly employed approximate technique with which one can examine spatially disordered systems when strong electronic correlations are present is based on the use of real-space...
Quantum phase transition induced by Dzyaloshinskii-Moriya in the kagome antiferromagnet (2008)
Cepas, O., Fong, C. M., Leung, P. W., Lhuillier, C.
We argue that the S=1/2 kagome antiferromagnet undergoes a quantum phase transition when the Dzyaloshinskii-Moriya coupling is increased. For $DD_c$ the system develops antiferromagnetic long-range...
Chen, X., Leung, P. W., Gooding, R. J.
We have obtained the exact ground state wave functions of the Anderson-Hubbard model for different electron fillings on a 4x4 lattice with periodic boundary conditions - for 1/2 filling such ground...
Magnon Dispersion and Anisotropies in SrCu$_2$(BO$_3$)$_2$ (2006)
Cheng, Y. F., Cepas, O., Leung, P. W., Ziman, T.
We study the dispersion of the magnons (triplet states) in SrCu$_2$(BO$_3$)$_2$ including all symmetry-allowed Dzyaloshinskii-Moriya interactions. We can reduce the complexity of the general...
Hole correlation and antiferromagnetic order in the t-J model (2005)
We study the t-J model with four holes on a 32-site square lattice using exact diagonalization. This system corresponds to doping level x=1/8. At the ``realistic'' parameter J/t=0.3, holes in the...
Charge carrier correlation in the electron-doped t-J model (2005)
We study the t-t'-t''-J model with parameters chosen to model an electron-doped high temperature superconductor. The model with one, two and four charge carriers is solved on a 32-site lattice using...
Absence of hole pairing in a simple t-J model on the Shastry-Sutherland lattice (2004)
The Shastry-Sutherland model is a two-dimensional frustrated spin model whose ground state is a spin gap state. We study this model doped with one and two holes on a 32-site lattice using exact...
Low-energy spectra in the t-J type models at light doping (2003)
Lee, Wei-Cheng, Lee, T. K., Ho, Chang-Ming, Leung, P. W.
Based on a variational approach, we propose that there are two kinds of low energy states in the t-J type models at low doping. In a quasi-particle state an unpaired spin bound to a hole with a...
We study the low energy states of the t-J model with two holes on a 32-site lattice with periodic boundary conditions. In contrary to common belief, we find that the state with d_{x^2-y^2} symmetry...
Utilization of Tactical Computers for Training: Field Evaluation Plan. (2002)
Hoyt,W. G., Butler,A. K., Leung,P. W.
This report describes Phase V in the development of TACFIRE Automated Instruction (AI) courseware. The overall project is aimed at extending the scope of CAI to the development of self-instructive...
Enhanced Bound State Formation in Two Dimensions via Stripe-Like Hopping Anisotropies (2000)
Basu, Saurabh, Gooding, R. J., Leung, P. W.
We have investigated two-electron bound state formation in a square two-dimensional t-J-U model with hopping anisotropies for zero electron density; these anisotropies are introduced to mimic the...
Signatures of a staggered-flux phase in the t-J model with two holes on a 32-site lattice (2000)
We study the relevance of the staggered-flux phase in the t-J model using a system with two holes on a 32-site lattice with periodic boundary conditions. We find a staggered-flux pattern in the...
Holes in the t-J_z model: a thorough study (1999)
Chernyshev, A. L., Leung, P. W.
The t-J_z model is the strongly anisotropic limit of the t-J model which captures some general properties of the doped antiferromagnets (AF). The absence of spin fluctuations simplifies the...
Utilization of Tactical Computers for Training: Summary Report. (1998)
Hoyt,W. G., Butler,A. K., Leung,P. W.
This is a summary report of the four previous reports which concerned itself with examining the feasibility of using computer-assisted instruction (CAI) as an embedded, individualized training...
Utilization of Tactical Computers for Training: Job/Task and Training Analysis. (1998)
Butler,A. K., Hoyt,W. G., Leung,P. W.
This Research Report presents the Phase II results in the development of TACFIRE Automated Instruction courseware. The overall aim of this report is to extend the scope of the application of computer...
Development of CAI Performance Measures: TACFIRE Tactical Data System. (1998)
Hoyt,W. G., Butler,A. K., Leung,P. W., Germas,J. E., Larson,John T.
This is the sixth and last report in the series which describes the utilization of tactical computers for training. This report summarizes the development of computer-assisted instruction (CAI)...
Butler,A. K., Hoyt,W. G., Leung,P. W.
This Research Report is an addendum to RR 1281. The functional area selected for research in this report is the ammunition and fire unit area. This report presents the training analysis results for...
A comprehensive numerical and analytical study of two holes doped into the 2D t-J model (1998)
Chernyshev, A. L., Leung, P. W., Gooding, R. J.
We report on a detailed examination of numerical results and analytical calculations devoted to a study of two holes doped into a two-dimensional, square lattice described by the t-J model. Our exact...
A numerical and analytical study of two holes doped into the 2D t--J model (1997)
Chernyshev, A. L., Leung, P. W., Gooding, R. J.
Exact diagonalization numerical results are presented for a 32-site square cluster, with two holes propagating in an antiferromagnetic background described by the t-J model. We characterize the wave...
Leung, P. W., Wells, B. O., Gooding, R. J.
We explore the success of various versions of the one-band t-J model in explaining the full spectral functions found in angle-resolved photoemission spectra for the prototypical, quasi...
Columnar dimer and plaquette resonating valence bond states of the quantum dimer model (1996)
Leung, P. W., Chiu, K. C., Runge, K. J.
We study the nature of the ground state of the quantum dimer model proposed by Rokhsar and Kivelson by diagonalizing the Hamiltonian of the model on square lattices of size $L\times L$, where $L\leq...
Dynamical properties of the single--hole $t$--$J$ model on a 32--site square lattice (1995)
We present results of an exact diagonalization calculation of the spectral function $A(\bf k, \omega)$ for a single hole described by the $t$--$J$ model propagating on a 32--site square cluster. The...
Numerical evidence for the spin-Peierls state in the frustrated quantum antiferromagnet (1995)
We study the spin-$1\over2$ Heisenberg antiferromagnet with an antiferromagnetic $J_3$ (third nearest neighbor) interaction on a square lattice. We numerically diagonalize this ``$J_1$-$J_3$'' model...
Quantum Antiferromagnets On The Triangular Lattice (1995)
this paper, we study the triangular HAF using the exact diagonalization approach. Since first-order SWT supports N'eel type ordering, we also study the second-order SWT to see if the same conclusion...
Theory of electron-hole asymmetry in doped {\em CuO$_2$} planes (1994)
The magnetic phase diagrams, and other physical characteristics, of the hole- doped {\em La$_{2-x}$Sr$_x$CuO$_4$} and electron-doped {\em Nd$_{2-x}$Ce$_x$ CuO$_4$} high-temperature superconductors...
Gooding, R. J., Vos, K. J. E., Leung, P. W.
We have calculated S(q) and the single particle distribution function for N holes in the t - J model on a non--square sqrt{8} X sqrt{32} 16--site lattice with periodic boundary conditions; we...