University of Iceland

h.D. defence in Chemistry - Sergei Y. Liashko

h.D. defence in Chemistry - Sergei Y. Liashko

When: 
Friday, December 8, 2017 - 14:00
Location: 
Location details: 
N-132

Ph.D. student: Sergei Y. Liashko.

Name of thesis: Temperature-induced magnetization reversals in micromagnetic systems.

Opponents

Prof. Robert L. Stamps, Chairman of the Dpt. of Physics, University of Manitoba, Canada.

Dr. Peter Derlet, Senior Scientist at the Paul Scherrer Institute in Switzerland.

Advisors:

Hannes Jónsson, Professor in the Faculty of Physical Sciences at the University of Iceland and Valery M. Uzdin, Professor in the Physics Department of  ITMO University in St. Petersburg.

Doctoral committee also included:

Pavel Bessarab, Research Specialist, Science Institute of the University of Iceland.

Unnar Arnalds, Research Specialist, Science Institute of the University of Iceland.

Chair of Ceremony:  Oddur Ingólfsson, head of Faculty of Physical Sciences.

Abstract: Microscopic magnetic particles play an important role in a wide range of systems, from asteroids in outer space and minerals in the Earth’s crust, to living organisms and modern technology such as digital data storage devices. An important task is to describe the behaviour of such particles at a given temperature and in the presence of an applied magnetic field. In this thesis, a theoretical method is developed for estimating the lifetime of magnetic states of microscopic particles based on harmonic transition state theory. It represents an extension of Stoner-Wohlfarth theory by introducing the effect of temperature. An analytical expression for the lifetime is presented as a function of magnetic field strength and temperature for certain field directions. Collections of micromagnetic particles in elements of spin ice systems are analysed and predicted lifetime of the ground state found to compare well with reported results of experimental measurements.

About the Ph.D. student: Sergei Liashko was born in 1990 in the town Vorkuta in Russia. He received an M.S. degree in Applied Mathematics and Computer Science from ITMO University in St. Petersburg in Russia in in 2013. He first entered the Ph.D. program at ITMO University but since the fall of 2015 he has been in a joint Ph.D. program with University of Iceland. His hobbies include history and swimming.

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