Investigation of the Inelastic Tunneling Current for Electron Tunneling Spectroscopy on a Chain of Magnetic Atoms

Investigation of the Inelastic Tunneling Current for Electron Tunneling Spectroscopy on a Chain of Magnetic Atoms

Assendelft, J.

Blaauboer, M. (mentor)

Applied Sciences

QN/Quantum Nanoscience

Theoretical Physics

2016-07-21

The aim of this report is to investigate the inelastic tunneling current that would be measured during an inelastic electron tunneling spectroscopy experiment performed on a one dimensional chain of magnetic atoms. A chain consisting of n magnetic iron atomswith spin 2 has been examined. The spins of the iron atoms in the chain have been treated quantum mechanically. The spins of the atoms in the chain are governed by the time independent spinHamiltonian. A method has been developed to find the eigenstates and eigenenergies of the Hamiltonian. The eigenstates of the Hamiltonian live in a 5n dimensional Hilbert space. The eigenstates and eigenenergies of the chain have been used to predict the inelastic tunneling current that would be measured during an inelastic electron tunneling spectroscopy experiment. Furthermore, the eigenstates have been investigated for ’spin waves’. Note that these ’spin waves’ are not waves in time, but wavelike ’motions’ in Hilbert space. Results show that the current increases when the voltage increases. The differential conductance exhibits a jump if a state transition occurs. A system with a high temperature has a higher current and the current starts increasing for lower voltages than a system with lower temperature. Changing the position of the STM tip changes the interaction with the chain, resulting in different state transitions to occur. The influence of the location of the STM tip is the same for symmetric atoms in the chain. Increasing the number of atoms in the chain causes more jumps in the differential conductance, but the jumps are smaller. Decreasing the number of atoms causes less jumps in the differential conductance, but the jumps are bigger. The eigenstates are superpositions of z-basis elements and wavelike ’motions’ occur in the eigenstates.

http://resolver.tudelft.nl/uuid:d82ff1e1-36a3-4d92-968d-eb4e5d167a27

Student theses

bachelor thesis

(c) 2016 Assendelft, J.