Spin dynamics from majorana fermions.

@article{Mao2003SpinDF,
  title={Spin dynamics from majorana fermions.},
  author={W. Mao and Piers Coleman and Chris A. Hooley and David C. Langreth},
  journal={Physical review letters},
  year={2003},
  volume={91 20},
  pages={
          207203
        }
}
Using the Majorana fermion representation of spin-1/2 local moments, we show how the dynamic spin correlation and susceptibility are obtained directly from the one-particle Majorana propagator. We illustrate our method by applying it to the spin dynamics of a nonequilibrium quantum dot, computing the voltage-dependent spin relaxation rate and showing that, at weak coupling, the fluctuation-dissipation relation for the spin of a quantum dot is voltage dependent. We confirm the voltage-dependent… 

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References

SHOWING 1-10 OF 15 REFERENCES
Spin-spin correlators in the majorana representation.
In the Majorana representation of a spin 1/2 we find an identity which relates spin-spin correlators to one-particle fermionic correlators. This should be contrasted with the straightforward approach
Majorana fermion representation for an antiferromagnetic spin-½ chain
We study the one-dimensional Heisenberg antiferromagnet with s = 1/2 using a Majorana representation of the s = 1/2 spins. A simple Hartree-Fock approximation of the resulting model gives a bilinear
Mean-field theory for the t-J model.
TLDR
A new mean-field theory for the /ital t/-/ital J/ model is presented using a representation in which singly occupied sites or spins are represented by bosons and empty sites or holes by fermions, with a clear separation of charge and spin excitations.
Perturbative expansion of the magnetization in the out-of-equilibrium Kondo model
This paper is concerned with the out-of-equilibrium two-lead Kondo model, considered as a model of a quantum dot in the Kondo regime. We revisit the perturbative expansion of the dot’s magnetization,
Theory of Spin Resonance in Dilute Magnetic Alloys
The scheme of Kadanoff and Baym is shown to be useful for the rigorous derivation of Bloch or Boltzmann equations for spin systems. The scheme is applied to a system of conduction electrons in a
Three-body bound states and the development of odd-frequency pairing.
TLDR
The low energy excitations of these modes are discussed, suggesting them as a possible explanation for the absence of anisotropy in the thermal conductivity of heavy fermion superconductors.
Is the quantum dot at large bias a weak-coupling problem?
TLDR
It is shown that the two-lead Kondo model for a dc-biased quantum dot in the Coulomb blockade regime retains its strong-coupling nature, even at bias voltages larger than the equilibrium Kondo temperature.
Functional integral theories of low-dimensional quantum Heisenberg models.
TLDR
This work investigates the low-temperature properties of the quantum Heisenberg models, both ferromagnetic and antiferromagnetic, in one and two dimensions, using Schwinger bosons and S=(1/2 fermions) and solves for their low-order thermodynamic properties.
Quantum field-theoretical methods in transport theory of metals
The authors review the Keldysh method of obtaining kinetic equations for normal and superconducting metals. The use of the method is illustrated by examples involving electron-impurity,
The Kondo Effect in a Quantum Dot out of Equilibrium
We study the Kondo effect in a quantum dot subject to an external ac field. The Kondo effect can be probed by measuring the dc current induced by an auxiliary dc bias ${V}_{\mathrm{dc}}$ applied
...
...