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Volumn 75, Issue 11, 2006, Pages

Mott transitions and d-wave superconductivity in half-filled-band Hubbard model on square lattice with geometric frustration

Author keywords

Antiferromagnetic correlation; Condensation energy; Frustration; High Tc cuprate; Hubbard model; Mott transition; Spin gap; Superconductivity; Variational Monte Carlo method

Indexed keywords


EID: 33847419873     PISSN: 00319015     EISSN: 13474073     Source Type: Journal    
DOI: 10.1143/JPSJ.75.114706     Document Type: Article
Times cited : (133)

References (91)
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    • For example, J. E. Hirsch: Phys. Rev. B 31 (1985) 4403.
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    • For example, B. Kyung and A.-M. S. Tremblay: Phys. Rev. Lett. 97 (2006) 046402, and references therein.
    • For example, B. Kyung and A.-M. S. Tremblay: Phys. Rev. Lett. 97 (2006) 046402, and references therein.
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    • 2/U, in addition to the zerothorder terms. See, A. B. Harris and R. V. Lange: Phys. Rev. 157 (1967) 295.
    • 2/U, in addition to the zerothorder terms. See, A. B. Harris and R. V. Lange: Phys. Rev. 157 (1967) 295.
  • 52
    • 33847397831 scopus 로고    scopus 로고
    • In the results of ref. 27, ΨqFS, even in one dimension, seems to induce a Mott transition between U/t, 4 and 16. We speculate that a longer-range doublon-holon binding factor is crucial in one dimension to reduce Uc down to zero
    • c down to zero.
  • 54
    • 33847395786 scopus 로고    scopus 로고
    • A. Koga, T. Yoshioka, N. Kawakami and H. Yokoyama: submitted to J. Magn. Magn. Mater. and Physica C.
    • A. Koga, T. Yoshioka, N. Kawakami and H. Yokoyama: submitted to J. Magn. Magn. Mater. and Physica C.
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    • In the present VMC procedure, if the energy barrier between the two local energy minima is sufficiently high, the optimized variational parameters are trapped in the local minima to which the initial parameter values tend. Thus, as seen in Figs. 3, 5, and 6, we can obtain the optimized values for both local minima by giving the respective initial parameters anticipated from those obtained for nearby data points. On the other hand, if the barrier becomes as low as the statistical fluctuation in E/t we assume there are still two energy minima, the parameters readily arrive at the global minima, jumping over the barrier. Therefore, it is not easy to determine the values of U/t at which the double-minimum structure of E/t vanishes, namely, to draw the accurate hysteresis curves
    • In the present VMC procedure, if the energy barrier between the two local energy minima is sufficiently high, the optimized variational parameters are trapped in the local minima to which the initial parameter values tend. Thus, as seen in Figs. 3, 5, and 6, we can obtain the optimized values for both local minima by giving the respective initial parameters anticipated from those obtained for nearby data points. On the other hand, if the barrier becomes as low as the statistical fluctuation in E/t (we assume there are still two energy minima), the parameters readily arrive at the global minima, jumping over the barrier. Therefore, it is not easy to determine the values of U/t at which the double-minimum structure of E/t vanishes, namely, to draw the accurate hysteresis curves.
  • 67
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    • -2). Thereby, we estimated approximate values of μ for L = ∞ and t′ = 0 as μ = 0:912-0:945 for U/t = 6.75-10; as U/t increases, μ tends to increase.
    • -2). Thereby, we estimated approximate values of μ for L = ∞ and t′ = 0 as μ = 0:912-0:945 for U/t = 6.75-10; as U/t increases, μ tends to increase.
  • 70
    • 33847376842 scopus 로고    scopus 로고
    • The behavior of n(k) for finite values of t′/t is basically the same. In some cases, however, the position of the (quasi) Fermi surface moves as U/t increases and crosses a discrete k-point of the finite system. Then, it becomes difficult to accurately determine the values of Z as a function of U/t, because the position of the Fermi surface is not specified. For instance, the case of t′/t = -0:25 and L = 14 exhibits such inconvenient behavior.
    • The behavior of n(k) for finite values of t′/t is basically the same. In some cases, however, the position of the (quasi) Fermi surface moves as U/t increases and crosses a discrete k-point of the finite system. Then, it becomes difficult to accurately determine the values of Z as a function of U/t, because the position of the Fermi surface is not specified. For instance, the case of t′/t = -0:25 and L = 14 exhibits such inconvenient behavior.
  • 71
    • 33847360001 scopus 로고    scopus 로고
    • In ref. 6, the optimized chemical potential ζ is positive, because the sign of t′/t is assumed positive, contrary to the present case. The behavior of |ζ| for U < Uc in ref. 6 is broadly similar to that in Fig. 4e, whereas for U > U c, ζ decreases to nearly zero, which is the value for t′/t, 0, but never becomes negative
    • c, ζ decreases to nearly zero, which is the value for t′/t = 0, but never becomes negative.
  • 74
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    • For 6,4 ≲ U/t < 6.64, Uc/t, ΨQd with t′/t, 0:4 and L, 10 has a special k-point configuration [observed in n(k, not shown, which is different from the cases of U/t ≤ 6:4, and is advantageous to SC. One finds in Fig. 4 that each of the optimized parameters for t′/t, 0.4 and L, 10 has a value similar to that which induces SC (e.g, t′/t| ≤ 0:3) only for 6.4 ≲ U/t < 6:64. Correspondingly, Pd(r) shown in Fig. 24(b) has extremely large values for the above values of U/t. This enhancement of SC is spurious, because there is no such remarkable behavior for L, 12 and 14. Such behavior sometimes appears near the critical value of t′/t, where predominant SC vanishes, and for specific system sizes, boundary conditions and model parameters. Also at this point, w
    • d(r) shown in Fig. 24(b) has extremely large values for the above values of U/t. This enhancement of SC is spurious, because there is no such remarkable behavior for L = 12 and 14. Such behavior sometimes appears near the critical value of t′/t, where predominant SC vanishes, and for specific system sizes, boundary conditions and model parameters. Also at this point, we need to check the system-size dependence.
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    • d(r) in eq. (21) is useful, because we are interested in the occurrence of SC, particularly, near the Mott transition.
    • d(r) in eq. (21) is useful, because we are interested in the occurrence of SC, particularly, near the Mott transition.
  • 76
    • 33847364388 scopus 로고    scopus 로고
    • As L is increased, the magnitude of spikes gradually decreases. We need to use the systems of L, 30-50 in which the spikes for U/t, 0 appear negligible on the scale of Fig. 23
    • As L is increased, the magnitude of spikes gradually decreases. We need to use the systems of L = 30-50 in which the spikes for U/t = 0 appear negligible on the scale of Fig. 23.
  • 78
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    • We adopt the Manhattan metric to measure |R| and |r|.
    • We adopt the Manhattan metric to measure |R| and |r|.
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    • T. Watanabe, H. Yokoyama, Y. Tanaka and J. Inoue: submitted to J. Magn. Magn. Mater., and in preparation.
    • T. Watanabe, H. Yokoyama, Y. Tanaka and J. Inoue: submitted to J. Magn. Magn. Mater., and in preparation.
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    • private communication
    • Y. C. Chen: private communication.
    • Chen, Y.C.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.