Spin Fluctuations in an Itinerant Heisenberg System : Naive RPA Treatment : Condensed Matter and Statistical Physics

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概要

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• The dynamical spin fluctuations in a two-dimensional square lattice in its paramagnetic phase are examined within the framework of Random Phase Approximation (RPA). Itinerant carriers with spin interact with each other via an antiferromagnetic Heisenberg interaction. Then there appear three fundamental scattering processes; a) scattering with spin-flip, b) scattering between parallel spins and c) scattering between antiparallel spins. To examine how these scattering processes affect the dynamical spin fluctuations, we pick up carefully all possible combination of RPA diagrams in a consistent manner and take the spin rotational symmetry into account. Then it becomes clear that we have to take up a sequence of the irreducible single loop which in itself is modified due to the particle-hole ladder type vertex correction. We set up the Bethe-Salpeter equation for the vertex correction and show that this can be solved in a closed form due to separable nature of the antiferromagnetic interaction. We evaluated numerically the effect of the vertex correction and found that the correction is negligibly small. Therefore we propose that in an itinerant Heisenberg system, including the t-J model as its derivative, the simplified RPA, where the irreducible single loop is nrenormalized, works very well. This conclusion strongly supports the simplified treatment which is widely used in High- T_c problem. Moreover the present formalism enables us to proceed further microscopic calculations on the magnetic properties in the current High- T_c problem.

• 理論物理学刊行会の論文
• 1995-10-25

著者

• KISHINE Junichiro

  Institute of Physics, College of Arts and Sciences University of Tokyo

• Kishine Junlchiro

  Institute Of Physics College Of Arts Aud Sciences University Of Tokyo

• KISHINE Junlchiro

  Institute of Physics, College of Arts aud Sciences University of Tokyo

関連論文

• Superconductivity of Carriers Doped into the Static Charge Density Wave State in 2-Dimensional Square Lattice
• Spin Gap of S=1/2 Heisenberg Ladder:Field Theoretical Study of Magnetic Susceptibility and NMR Relazation Rate
• Spin Fluctuations in an Itinerant Heisenberg System : Naive RPA Treatment : Condensed Matter and Statistical Physics

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