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Magnetization dynamics in nanorings

Ydman, Simon LU (2015) FYSM31 20151
Department of Physics
Mathematical Physics
Abstract
This thesis investigates numerically the out of equilibrium properties of quantum rings with magnetic impurities, using the periodic Anderson model (PAM). The model is a simple template for the discussion of the physics of regular arrays of rare-earth impurities in metallic hosts. The system considered is a quantum ring consisting of up to six sites, each of whom are connected to an Anderson impurity site. The dynamical properties of this system are investigated numerically using exact diagonalization and Lanczos adapted time evolution. Two different schemes are used to perturb the system: a magnetic field piercing the ring and a local Zeeman interaction at one of the conduction sites. Comparisons are made with a ring without impurities,... (More)
This thesis investigates numerically the out of equilibrium properties of quantum rings with magnetic impurities, using the periodic Anderson model (PAM). The model is a simple template for the discussion of the physics of regular arrays of rare-earth impurities in metallic hosts. The system considered is a quantum ring consisting of up to six sites, each of whom are connected to an Anderson impurity site. The dynamical properties of this system are investigated numerically using exact diagonalization and Lanczos adapted time evolution. Two different schemes are used to perturb the system: a magnetic field piercing the ring and a local Zeeman interaction at one of the conduction sites. Comparisons are made with a ring without impurities, and it is shown that for very strong onsite interaction and/or very weak hybridization between the conduction sites and the impurity sites, the physics of a ring without impurities is recovered. Furthermore, a Doniach-type phase diagram in the presence of persistent currents, is provided where it is shown that the Kondo regime is reached for smaller values of the hybridization parameter when a magnetic field piercing the ring is present. The Doniach phase diagram is discussed in connection with persistent currents and entanglement. Preliminary results for the Zeeman field suggests a non trivial interplay between charge and spin currents, and RKKY and Kondo-like couplings. (Less)
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author
Ydman, Simon LU
supervisor
organization
course
FYSM31 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Kondo effect, quantum rings, doniach phase diagram, exact diagonalization
language
English
id
7373510
date added to LUP
2015-06-24 22:15:08
date last changed
2015-06-24 22:15:08
@misc{7373510,
  abstract     = {This thesis investigates numerically the out of equilibrium properties of quantum rings with magnetic impurities, using the periodic Anderson model (PAM). The model is a simple template for the discussion of the physics of regular arrays of rare-earth impurities in metallic hosts. The system considered is a quantum ring consisting of up to six sites, each of whom are connected to an Anderson impurity site. The dynamical properties of this system are investigated numerically using exact diagonalization and Lanczos adapted time evolution. Two different schemes are used to perturb the system: a magnetic field piercing the ring and a local Zeeman interaction at one of the conduction sites. Comparisons are made with a ring without impurities, and it is shown that for very strong onsite interaction and/or very weak hybridization between the conduction sites and the impurity sites, the physics of a ring without impurities is recovered. Furthermore, a Doniach-type phase diagram in the presence of persistent currents, is provided where it is shown that the Kondo regime is reached for smaller values of the hybridization parameter when a magnetic field piercing the ring is present. The Doniach phase diagram is discussed in connection with persistent currents and entanglement. Preliminary results for the Zeeman field suggests a non trivial interplay between charge and spin currents, and RKKY and Kondo-like couplings.},
  author       = {Ydman, Simon},
  keyword      = {Kondo effect,quantum rings,doniach phase diagram,exact diagonalization},
  language     = {eng},
  note         = {Student Paper},
  title        = {Magnetization dynamics in nanorings},
  year         = {2015},
}