Abstract/Details

Disorder effects in spin systems: Diluted magnetic semiconductors and the aging dynamics of spin glasses


2002 2002

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Abstract (summary)

Spin glasses and diluted magnetic semiconductors are both materials whose magnetic properties are strongly influenced by disorder. In spin glasses, the interplay of disorder and frustration in the interactions between spins leads to exceptionally slow spin relaxation and intrinsically non-equilibrium (aging) dynamics. A new approach to understanding the aging dynamics of short-range spin glass models is introduced here. It is shown that the dynamics have a symmetry under time reparametrizations, and the soft modes in the system are identified as spatially varying time reparametrizations. This leads to a number of predictions for the scaling properties of local quantities that are found to be in good agreement with numerical simulations. In diluted magnetic semiconductors, magnetic ions introduced into the host semiconductor have random positions. Monte Carlo simulations performed on an impurity band model for diluted magnetic semiconductors indicate that the positional disorder of the magnetic ions leads to an inhomogeneous ferromagnetic state. It is conjectured that many of the observed properties of diluted magnetic semiconductors can be understood using a two-component model, in which manganese spins are either strongly or weakly involved in the ferromagnetism depending on their local environment.

Indexing (details)


Subject
Condensation
Classification
0611: Condensation
Identifier / keyword
Pure sciences; Aging; Disordered magnetic; Magnetic semiconductors; Spin glasses
Title
Disorder effects in spin systems: Diluted magnetic semiconductors and the aging dynamics of spin glasses
Author
Kennett, Malcolm Piers
Number of pages
255
Publication year
2002
Degree date
2002
School code
0181
Source
DAI-B 63/07, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780493756691, 0493756698
Advisor
Bhatt, Ravin N.
University/institution
Princeton University
University location
United States -- New Jersey
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3060075
ProQuest document ID
305526729
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305526729/abstract
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