On the nature of the magnetic transition in a Mott insulator
- 77 Downloads
Using a combination of exact enumeration and the dynamical mean-field theory (DMFT) we study the drastic change of the spectral properties, obtained in the half-filled two-dimensional Hubbard model at a transition from an antiferromagnetic to a paramagnetic Mott insulator, and compare it with the results obtained using the quantum Monte Carlo method. The coherent hole (electron) quasiparticle spin-polaron subbands are gradually smeared out when the AF order disappears, either for increasing Coulomb repulsion U at fixed temperature T, or for increasing T at fixed U. Within the DMFT we present numerical evidence (a continuous disappearence of the order parameter) suggesting that the above magnetic transition is second order both in two and in three dimensions.
KeywordsMonte Carlo Method Spectral Property Drastic Change Exact Enumeration Hubbard Model
Unable to display preview. Download preview PDF.
- 2.D.B. McWhan, A. Menth, J.P. Remeika, W.F. Brinkman, T.M. Rice, Phys. Rev. Lett. 27, 941 (1971); W. Bao, C. Broholm, G. Aeppli, P. Dai, J.M. Honig, P. Metcalf, Phys. Rev. Lett. 78, 507 (1997); W. Bao, C. Broholm, G. Aeppli, S.A. Carter, P. Dai, T.F. Rosenbaum, J.M. Honig, P. Metcalf, S.F. Trevino, Phys. Rev. B 58, 12727 (1998)CrossRefGoogle Scholar
- 4.J. Hubbard, Proc. Roy. Soc. Lond. A 276, 238 (1963)Google Scholar
- 15.It was also suggested that a continuous transition takes place in the infinite-dimensional Hubbard model [J. Schlipf, M. Jarrell, P.G.J. van Dongen, N. Blümer, S. Kehrein, T. Prushke, D. Vollhardt, Phys. Rev. Lett. 82, 4890 (1999)], but an accurate treatment of reference  gives the phase coexistence in the low temperature regime and shows that this transition is first orderCrossRefGoogle Scholar
- 17.M.J. Rozenberg, R. Chitra, G. Kotliar, Phys. Rev. Lett. 83, 3498 (1999)Google Scholar
- 19.C. Gros, W. Wenzel, R. Valent\’i, G. Hülsenbeck, J. Stolze, Europhys. Lett. 27, 299 (1994)Google Scholar
- 31.As a consequence of the local self-energy, the Green’s functions found along the AF BZ are degenerate in the DMFT, while in reality they are only nearly degenerate, as obtained in the 2D-QMC methodGoogle Scholar
- 33.This hysteresis appears in a range of U values in which two locally stable solutions of the DMFT equations exist: a global minimum for the antiferromagnetic state, and a local minimum for the paramagnetic stateGoogle Scholar
- 34.Equation (8) is based on experimental data, and was introduced by G.S. Rushbrooke, P.J. Wood, Mol. Phys. 1, 257 (1958); more discussion is given in: “Ferromagnetism” in Encyclopedia of Physics\/, edited by H.P.J. Wijn (Springer, Berlin, 1966), Vol. XVIII/2, pp. 1-273Google Scholar