Weak randomness in geometrically frustrated systems: spin-glasses

We study the competition between the spin-glass (SG) phase and antiferromagnetic (AF), superantiferromagnetic or ferromagnetic (FE) order in geometrically frustrated systems. We consider a model with two types of frustration: one coming from disordered interactions (J) and another coming from the sq...

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Bibliographic Details
Published in:Physica scripta 2015-02, Vol.90 (2), p.25809-5
Main Authors: Schmidt, M, Zimmer, F M, Magalhaes, S G
Format: Article
Language:English
Subjects:
Approximation
Clusters
Correlation
Curie temperature
disorder
Ferromagnetism
Frustration
geometrical frustration
Mathematical analysis
Phase diagrams
spin-glass
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Summary:We study the competition between the spin-glass (SG) phase and antiferromagnetic (AF), superantiferromagnetic or ferromagnetic (FE) order in geometrically frustrated systems. We consider a model with two types of frustration: one coming from disordered interactions (J) and another coming from the square-lattice Ising spin system with first-(J1) and second-(J2) neighbor interactions (intrinsic frustration). The disordered interactions are between clusters and they follow the van Hemmen model, which represents a limit of weak frustration. The cluster mean-field approximation is used to treat the short-range intercluster interactions. Results are exhibited in phase diagrams of the temperature T versus J for several values of . When the intrinsic frustration increases, the Néel and Curie temperatures decrease at the same time so that the SG phase appears at a lower J. Moreover, the FE correlations enhance the SG behavior, while AF correlations reduce the SG region at the same level of intrinsic frustration. These results indicate that a weak disorder in geometrically frustrated systems is able to stabilize the SG phase.
ISSN:0031-8949
1402-4896
DOI:10.1088/0031-8949/90/2/025809