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… 
View on PubMed
arxiv.org
31 Citations
Background Citations
3
Methods Citations
3

Figures from this paper

31 Citations

Majorana representation for dissipative spin systems
Using Majorana spin-1/2 representation for the spin-boson model
The Majorana representation for spin operators enables efficient application of field-theoretical methods for the analysis of spin dynamics. Moreover, a wide class of spin correlation functions can…
Nonequilibrium Transport through a Kondo Dot: Decoherence Effects.
We investigate the effects of voltage induced spin-relaxation in a quantum dot in the Kondo regime. Using nonequilibrium perturbation theory, we determine the joint effect of self-energy and vertex…
Energy current and its statistics in the nonequilibrium spin-boson model: Majorana fermion representation
We study the statistics of thermal energy transfer in the nonequilibrium (two-bath) spin-boson model. This quantum many-body impurity system serves as a canonical model for quantum energy transport.…
Dynamical spin-spin correlation functions in the Kondo model out of equilibrium
We calculate the dynamical spin-spin correlation functions of a Kondo dot coupled to two noninteracting leads held at different chemical potentials. To this end we generalize a recently developed…
Magnetotransport in the Kondo model with ferromagnetic exchange interaction
We consider the transport properties in an applied magnetic field of the spin S=1/2 Kondo model with ferromagnetic exchange coupling to electronic reservoirs, a description relevant for the strong…
Quantum heat transport in a spin-boson nanojunction: Coherent and incoherent mechanisms
Quantum heat transport in a spin-boson system under nonequilibrium steady state (NESS) is investigated by the nonequilibrium Green's function (NEGF) method. Spin-spin correlators are calculated via…
Majorana path integral for nonequilibrium dynamics of two-level systems
We present a new field-theoretic approach to analyze nonequilibrium dynamics of two-level systems (TLS), which is based on a correspondence between a driven TLS and a Majorana fermion field theory…
Spin transport in a quantum spin orbital liquid
Quantum spin-orbital liquids (QSOLs) are a novel phase of matter, similar to quantum spin liquids, with quantum fluctuations in both spin and orbital degress of freedom. We use non-equilibrium…
Exact chiral-spin-liquid state in a Kitaev-type spin model
We study a frustrated two-dimensional lattice spin model with Kitaev type interaction. The lattice is obtained from the honeycomb lattice by replacing half of its sites with triangles. Using the…
...
...

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…
...
...