Journal ArticleDOI
Anomalous magnetic structures and phase transitions in non-Heisenberg magnetic materials
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TLDR
In this paper, a discussion of isotropic magnetic materials with localized magnetic moments between which the exchange interaction is more complex than in the usual Heisenberg model is presented, and experimental data on these materials and their theoretical interpretation are given.Abstract:
This review is primarily devoted to a discussion of isotropic magnetic materials with localized magnetic moments between which the exchange interaction is more complex than in the usual Heisenberg model. They include insulators for which the biquadratic or multispin exchange mechanisms are comparable with the bilinear exchange, conductors which do not satisfy the conditions of validity of the RKKY indirect exchange theory, and the nuclear magnetic material solid helium. Additionally, an analysis is made of high-anisotropy magnetic materials behaving similarly to isotropic non-Heisenberg materials. These anisotropic materials have anomalous properties, compared with the Heisenberg case. Experimental data on these materials and their theoretical interpretation are given. The following topics are discussed: 1) the conditions for a strong non-Heisenberg exchange and non-Heisenberg Hamiltonians; 2) quadrupole ordering and order-proper disorder phase transitions; 3) order-order and order-improper disorder phase transitions; 4) metamagnetism of isotropic materials; 5) normal sequences and "devil's ladders" of phase transitions between commensurable structures; 6) canted antiferromagnetism of high-symmetry crystals which do not obey the condition for the existence of relativistic Dzyaloshinskiĩ-type interactions.read more
Citations
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Domain Observations on FeCrFe Layered Structnres. Evidence for a Biquadratic Coupling Effect
TL;DR: In this article, an epitaxial iron sandwich with a wedge shaped chromium interlayer is analyzed using magneto-optical techniques and an interpretation of these patterns invokes coupling between the iron layers which favours a right angle between the magnetization directions in both layers.
Journal ArticleDOI
Unusual phases in quantum spin-1 systems
TL;DR: In this article, a more flexible semiclassical theory is developed based on a 1 n expansion, which predicts the occurrence of a nematic and a semi-ordered phase, in addition to the usual ferromagnetism and antiferromagnetic behavior.
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Effects of the nanocrystalline state in solids
TL;DR: In this article, the effect of the nanocrystalline state on the mechanical, thermal, and magnetic properties and microscopic structure of metals and solid-phase compounds are reviewed and the importance of interfaces in determining the structure and properties of compact nanomaterials is demonstrated.
Journal ArticleDOI
Consistent model of magnetism in ferropnictides
TL;DR: In this article, the addition of a biquadratic interaction term to the usual Heisenberg Hamiltonian leads to a description of many experimental observations, such as magnetic properties of pnictide superconductors.
Journal ArticleDOI
Biquadratic exchange interactions in two-dimensional magnets
TL;DR: In this article, the authors demonstrate that biquadratic exchange interactions, which is the simplest and most natural form of non-Heisenberg coupling, assume a key role in the magnetic properties of layered magnets.
References
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Book
Introduction to Phase Transitions and Critical Phenomena
H. Eugene Stanley,Guenter Ahlers +1 more
TL;DR: In this article, the authors present a paperback edition of a distinguished book, originally published by Clarendon Press in 1971, which is at the level at which a graduate student who has studied condensed matter physics can begin to comprehend the nature of phase transitions, which involve the transformation of one state of matter into another.
Book
Fractals: Form, Chance and Dimension
TL;DR: Fractals as mentioned in this paper is a new field of mathematics that models the most interdisciplinary grab-bag of naturally occurring forms, such as coastlines and clouds, crystals, snowflakes and cosmological structures.
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Biquadratic Exchange and the Behavior of Some Antiferromagnetic Substances
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Phase diagram and magnetic structures of CeSb
TL;DR: In this article, the magnetic structures of the various observed Cerium pnictides phases have been determined and three types of structures can be distinguished: (a) at low temperature only $M\ensuremath{\uparrow}$ and $P$ planes exist.
Journal ArticleDOI
Magnetic ordering in cerium and uranium monopnictides
TL;DR: In this article, the magnetic phase diagram of CeSb and CeBi is presented and analyzed within the framework of the layered Ising model, and the implications of this model to uranium monopnictides are discussed.