TY - JOUR

T1 - Magnetic and metal-insulator transitions through bandwidth control in two-dimensional Hubbard models with nearest and next-nearest neighbor transfers

AU - Kashima, Tsuyoshi

AU - Imada, Masatoshi

PY - 2001/10/1

Y1 - 2001/10/1

N2 - Numerical studies on Mott transitions caused by the control of the ratio between bandwidth and electron-electron interaction (U) are reported. By using the recently proposed path-integral renormalization group (PIRG) algorithm, physical properties near the transitions in the ground state of two-dimensional half-filled models with the nearest and the next-nearest neighbor transfers (-t and t′, respectively) are studied as a prototype of geometrically frustrated system. The nature of the bandwidth-control transitions shows sharp contrast with that of the filling-control transitions: First, the metal-insulator and magnetic transitions are separated each other and the metal-insulator (MI) transition occurs at smaller U, although the both transition interactions U increase with increasing t′. Both transitions do not contradict the first-order transitions for smaller t′/t while the MI transitions become continuous type accompanied by emergence of unusual metallic phase near the transition for large t′/t. A nonmagnetic insulator phase is stabilized between MI and AF transitions. The region of the nonmagnetic insulator becomes wider with increasing t′/t. The phase diagram naturally connects two qualitatively different limits, namely the Hartree-Fock results at small t′/t and speculations in the strong coupling Heisenberg limit.

AB - Numerical studies on Mott transitions caused by the control of the ratio between bandwidth and electron-electron interaction (U) are reported. By using the recently proposed path-integral renormalization group (PIRG) algorithm, physical properties near the transitions in the ground state of two-dimensional half-filled models with the nearest and the next-nearest neighbor transfers (-t and t′, respectively) are studied as a prototype of geometrically frustrated system. The nature of the bandwidth-control transitions shows sharp contrast with that of the filling-control transitions: First, the metal-insulator and magnetic transitions are separated each other and the metal-insulator (MI) transition occurs at smaller U, although the both transition interactions U increase with increasing t′. Both transitions do not contradict the first-order transitions for smaller t′/t while the MI transitions become continuous type accompanied by emergence of unusual metallic phase near the transition for large t′/t. A nonmagnetic insulator phase is stabilized between MI and AF transitions. The region of the nonmagnetic insulator becomes wider with increasing t′/t. The phase diagram naturally connects two qualitatively different limits, namely the Hartree-Fock results at small t′/t and speculations in the strong coupling Heisenberg limit.

KW - Geometrical frustration

KW - Hubbard model

KW - J -j model

KW - Magnetic transition

KW - Metal-insulator transition

KW - Mott transition

KW - Quantum phase transition

KW - Quantum simulation

KW - Spin liquid

KW - Strongly correlated electron

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U2 - 10.1143/JPSJ.70.3052

DO - 10.1143/JPSJ.70.3052

M3 - Article

AN - SCOPUS:0035642948

VL - 70

SP - 3052

EP - 3067

JO - Journal of the Physical Society of Japan

JF - Journal of the Physical Society of Japan

SN - 0031-9015

IS - 10

ER -