The effect of a Zeeman magnetic field coupled to the spin of the electrons on the conducting properties of the disordered Hubbard model is studied. Using the determinant quantum Monte Carlo method,... Show moreThe effect of a Zeeman magnetic field coupled to the spin of the electrons on the conducting properties of the disordered Hubbard model is studied. Using the determinant quantum Monte Carlo method, the temperature- and magnetic-field-dependent conductivity is calculated, as well as the degree of spin polarization. We find that the Zeeman magnetic field suppresses the metallic behavior present for certain values of interaction and disorder strength and is able to induce a metal-insulator transition at a critical field strength. It is argued that the qualitative features of magnetoconductance in this microscopic model containing both repulsive interactions and disorder are in agreement with experimental findings in two-dimensional electron and hole gases in semiconductor structures. Show less
The effect of a Zeeman magnetic field coupled to the spin of the electrons on the conducting properties of the disordered Hubbard model is studied. Using the determinant quantum Monte Carlo method,... Show moreThe effect of a Zeeman magnetic field coupled to the spin of the electrons on the conducting properties of the disordered Hubbard model is studied. Using the determinant quantum Monte Carlo method, the temperature- and magnetic-field-dependent conductivity is calculated, as well as the degree of spin polarization. We find that the Zeeman magnetic field suppresses the metallic behavior present for certain values of interaction and disorder strength and is able to induce a metal-insulator transition at a critical field strength. It is argued that the qualitative features of magnetoconductance in this microscopic model containing both repulsive interactions and disorder are in agreement with experimental findings in two-dimensional electron and hole gases in semiconductor structures. Show less
Batrouni, G.G.; Rousseau, V.; Scalettar, R.T.; Rigol, M.; Muramatsu, A.; Denteneer, P.J.H.; Troyer, M. 2002
The understanding of the interplay of electron correlations and randomness in solids is enhanced by demonstrating that particle-hole ( p−h) symmetry plays a crucial role in determining the effects... Show moreThe understanding of the interplay of electron correlations and randomness in solids is enhanced by demonstrating that particle-hole ( p−h) symmetry plays a crucial role in determining the effects of disorder on the transport and thermodynamic properties of the half-filled Hubbard Hamiltonian. We show that the low-temperature conductivity decreases with increasing disorder when p−h symmetry is preserved, and shows the opposite behavior, i.e., conductivity increases with increasing disorder, when p−h symmetry is broken. The Mott insulating gap is insensitive to weak disorder when there is p−h symmetry, whereas in its absence the gap diminishes with increasing disorder. Show less
Denteneer, P.J.H.; Scalettar, R.T.; Trivedi, N. 1999
We calculate the spin stiffness of the S= frustrated Heisenberg antiferromagnet directly from a general formula which is evaluated in the Schwinger-boson mean-field approximation. Both Néel and... Show moreWe calculate the spin stiffness of the S= frustrated Heisenberg antiferromagnet directly from a general formula which is evaluated in the Schwinger-boson mean-field approximation. Both Néel and collinear ordering are considered. For collinear ordering, we take the anisotropy of this phase into account, unlike previous approaches. For Néel ordering, a detailed study is made of the finite-size scaling behavior of the two terms that make up the spin stiffness. The exponents of the scaling with the system size of the two terms comprising the spin stiffness turn out to be identical to those of the unfrustrated case. Show less
The microscopic structures of hydrogen-antimony, -tellurium, and -tin complexes in silicon have been studied using first-principles total-energy calculations, in order to obtain a more definitive... Show moreThe microscopic structures of hydrogen-antimony, -tellurium, and -tin complexes in silicon have been studied using first-principles total-energy calculations, in order to obtain a more definitive understanding of the various dopant-hydrogen complexes in n-type crystalline silicon. We find that for neutral SbH, TeH, and SnH complexes, the lowest-energy configurations are similar and of the type AB-Si (the H is located at the antibonding site of a Si atom that is adjacent to the impurity). The reaction SbH + H→SbH2 turns out to be exothermic. The results are consistent with recent experimental results using Mössbauer spectroscopy. For SbH2 various configurations are found that differ only slightly in energy. The lowest-energy configuration of SbH2 complexes exhibits electrical properties similar to those of substitutional Sb. This suggests that the formation of SbH2 not only competes with that of SbH and H*2, but may also electrically activate the sample. Show less
We derive low-temperature properties of the large-U Hubbard model in two and three dimensions starting from exact series-expansion results for high temperatures. Convergence problems and limited... Show moreWe derive low-temperature properties of the large-U Hubbard model in two and three dimensions starting from exact series-expansion results for high temperatures. Convergence problems and limited available information prevent a direct or Padé-type extrapolation. We propose a method of extrapolation, which is restricted to large U and low hole densities, for which the problem can be mapped on that of a system of weakly interacting holes. In this formulation an extrapolation down to T=0 can be obtained, but it can be trusted for the presently available series data for βt≲20 and for hole densities nh≲0.2 only. Implications for the magnetic phase diagram are discussed. Show less
