Methods of Computer Science and Statistical Physics in the study of Disordered Systems

Doctoral Dissertation uoadl:1309166 641 Read counter

Unit:
Τομέας Φυσικής Συμπυκνωμένης Ύλης
Library of the School of Science
Deposit date:
2016-06-03
Year:
2016
Author:
Παπακωνσταντίνου Θεόδωρος
Dissertation committee:
Ιωάννης Χατζηαγαπίου Αναπλ. Καθηγητής (Επιβλέπων), Κωσταντίνος Παρασκευαΐδης Αναπλ. Καθηγητής, Ιωάννης Λελίδης Επίκ. Καθηγητής
Original Title:
Μέθοδοι Υπολογιστικής Επιστήμης και Στατιστικής Φυσικής στη μελέτη Συστημάτων Αταξίας
Languages:
Greek
Translated title:
Methods of Computer Science and Statistical Physics in the study of Disordered Systems
Summary:
We present the study of critical behavior of disordered Ising systems, without
frustration like the random bond Blume-Capel model along with two anisotropic
spin glass Edwards-Anderson (EA) models. Especially in the cubic random bond BC
model we studied the influence of disorder on the first and second order
ferromagnetic paramagnetic transitions. We observed violation of universality
since the immerged two second order transitions did not belong in the same
universality class. For the anisotropic EA models their respective phase
diagrams were constructed. We studied the criticality of all the three phase
transitions (ferromagnetic-paramagnetic, paramagnetic-spin glass and
ferromagnetic-spin glass).
We found that the all transitions belong to the universality classes of the
isotropic model. Particularly we accurately confirmed that the F-P transition
belongs to the universality of the random Ising model. For the symmetric case
of the phase diagrams we observed that both critical temperature and ground
state energy of the transverse and isotropic model coincided while the same
quantities of the longitudinal anisotropic model differ. The findings were
interpreted and the role of frustration in spin glass systems was illustrated.
Keywords:
Spin glass, Disorder, Statistical physics, Phase transitions, Frustration
Index:
No
Number of index pages:
0
Contains images:
Yes
Number of references:
184
Number of pages:
XVI, 165
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