Teória spinových retiazok na povrchu kovu: emergencia ťažkých fermiónov

• Thesis title in Czech: Teória spinových retiazok na povrchu kovu: emergencia ťažkých fermiónov
• Thesis title in English: Theory of spin chains on metallic surfaces: emergence of the heavy-fermion behavior
• English key words: Kondo effect slave-boson mean-field Anderson Hamiltonian heavy fermions
• Academic year of topic announcement: 2019/2020
• Type of assignment: diploma thesis
• Department: Department of Condensed Matter Physics (32-KFKL)
• Supervisor: Ing. Richard Korytár, Ph.D.

Guidelines

The problem will be formulated in terms of a multiple-impurity Anderson model.
An approximate solution of the strongly-correlated problem may be formulated in terms of a slave-boson mean-field theory.
The latter will be implemented and solved numerically.
The local spectral function and its (k-space) Fourier transform will be the principal descriptors of the onset of the heavy-fermion behavior.
Optionally, one could simulate the local spectral function of surface electrons in order to compare with the experimental results of the scanning-tunneling microscopy.

References

THEORY:
Heavy Fermions and the Kondo Lattice: a 21st Century Perspective, P. Coleman, Lecture notes for Autumn School on Correlated Electrons: Many-Body Physics: From Kondo to Hubbard. Julich 21-25 Sept, 2015, https://arxiv.org/abs/1509.05769

METHODS:
Mean-field theory of intermediate valence/heavy fermion systems, Newns, D. M. and Read, N., Advances in Physics, 36:6, 799 (1987)

INTERESTING EXPERIMENTS:
Spin coupling in engineered atomic structures, CF Hirjibehedin, CP Lutz, AJ Heinrich, Science 312, 1021 (2006)
Real-Space Imaging of Kondo Screening in a Two-Dimensional O2 Lattice, Ying Jiang, Y. N. Zhang, J. X. Cao, R. Q. Wu, W. Ho, Science (2011) Vol. 333, Issue 6040, pp. 324, DOI: 10.1126/science.1205785

Preliminary scope of work in English

When a magnetic moment is embedded in a metallic (free-electron) environment, spin-fluctuations give rise to a Kondo effect: excitations at low temperatures are free-fermion like and the magnetic moment is quenched. Similarly, a lattice of magnetic moments (plus the metallic environment) can lead to a heavy-fermion behavior, characterized by a new (heavy) electron band and suppression of magnetism.

In this project we want to study theoretically the evolution from the single-moment Kondo effect to a multiple-moment lattice (spin chains) and investigate the onset of heavy-fermion phenomenology as the chain length increases.
This study is inspired by a collaboration with an experimental group at the University of Zaragoza (David Serrate) (scanning-tunneling microscopy of atomic spin-chains on a metallic surface).