Correlation effects in a band ferromagnet: spin-rotationally-symmetric study with self-energy and vertex corrections

نویسنده

  • Avinash Singh
چکیده

Quantum corrections to the transverse spin-fluctuation propagator are obtained by including self-energy and vertex corrections to first order within a spin-rotationallysymmetric inverse-degeneracy (1/N ) expansion scheme which preserves the Goldstone mode order by order. A correlation-induced exchange-energy correction is shown to yield the dominant quantum reduction in the spin stiffness, providing a quantitative understanding of the ferromagnetic-state stability in terms of simple lattice-dependent features of energy-band dispersion. The quantum reduction factor U/W highlights the subtlety in the characteristic competition in a band ferromagnet between interaction U and bandwidth W .

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Self-dual Chern-Simons Solitons in the Planar Ferromagnet

We consider a uniaxial planar ferromagnet coupled minimally to an Abelian ChernSimons gauge field and study self-dual solitons which saturate the Bogomol’nyi bound. We find a rich structure of rotationally symmetric static soliton solutions for various uniform background charge densities. For a given ferromagnet material, the properties of these solitons are controlled only by the external magn...

متن کامل

Role of vertex corrections in the spin-fluctuation mediated pairing mechanism

– We study numerically and partly diagrammatically the renormalization of the electron-spin interaction or vertex in a two-dimensional one-band Hubbard model with spinfluctuation momentum transfer q = (π, π). We find that the renormalized electron-spin vertex decreases quite generally with decreasing temperature at all doping densities. As a combination of two concurring effects, i.e. the decre...

متن کامل

Weak versus strong universality in the two-dimensional random-bond Ising ferromagnet.

We address the issue of universality in two-dimensional disordered Ising systems, by considering long, finite-width strips of ferromagnetic Ising spins with randomly distributed couplings. We calculate the free energy and spin-spin correlation functions ~from which averaged correlation lengths, j, are computed! by transfer-matrix methods. An ansatz for the size dependence of logarithmic correct...

متن کامل

Improved estimators for the self-energy and vertex function in hybridization-expansion continuous-time quantum Monte Carlo simulations

We propose efficient measurement procedures for the self-energy and vertex function of the Anderson impurity model within the hybridization expansion continuous-time quantum Monte Carlo algorithm. The method is based on the measurement of higher-order correlation functions related to the quantities being sought through the equation of motion, a technique previously introduced in the numerical r...

متن کامل

M ay 1 99 8 What are the experimentally observable effects of vertex corrections in superconductors ?

What are the experimentally observable effects of vertex corrections in superconductors? Abstract We calculate the effects of vertex corrections, of non-constant density of states and of a (self-consistently determined) phonon self-energy for the Holstein model on a 3D cubic lattice. We replace vertex corrections with a Coulomb pseudopotential, µ * C , adjusted to give the same T c , and repeat...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2006