Planar lattices of magnetic nanoparticles with antiferromagnetic interaction
- PDF / 747,925 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 42 Downloads / 206 Views
ICE DYNAMICS AND PHASE TRANSITIONS
Planar Lattices of Magnetic Nanoparticles with Antiferromagnetic Interaction A. M. Shutyi* and D. I. Sementsov Ulyanovsk State University, Ulyanovsk, 432017 Russia *e-mail: [email protected] Received October 28, 2015
Abstract—Square lattices of magnetic nanoparticles undergoing dipole–dipole and antiferromagnetic exchange interactions have been investigated. The main types of equilibrium states with zero and nonzero total magnetic moments have been revealed. It is shown that transitions between different equilibrium states may occur by means of a uniform magnetic field due to the presence of configuration bistability. Orientational transitions between equilibrium states under the action of a magnetic-field pulse on the system and transient oscillation processes have been studied. DOI: 10.1134/S1063774517040228
INTRODUCTION Magnetic systems are convenient objects for analyzing self-organization processes [1, 2] and studying collective effects, phase transitions, and dynamic modes [3, 4] due to the possibility of effective control of their state. Ensembles of nanoparticles are of great interest because of the advances in information technologies. In the recent years, magnetic superstructures and ensembles of single-domain magnetic particles produced by nanotechnologies have been systematically studied and implemented in practice [5]. Systems of magnetic particles are important objects of study because of the possibility of creating new media upon incorporation of particles into solid-state porous matrices [6, 7]. Ordered nanoparticle structures can be formed by nanolithography [8] using dipoles composed of iron atoms. The main contribution to the interaction between magnetic moments in such systems is made by dipole– dipole and exchange interactions [8, 9]. The ratio of energies of the dipole–dipole and exchange interactions is about 0.1–0.3 for crystalline magnets [10, 11], whereas for composite materials it may be as high as unity [12]. In systems of magnetic nanoparticles, the exchange interaction cannot be as strong as in magnetic crystals, where the distance between atoms is equal to the lattice parameter, and the exchange energy is much higher than the dipole-interaction energy [13, 14]. Nevertheless, this interaction may affect the behavior of a magnetic subsystem in nanostructured objects. Moreover, the exchange and dipole–dipole interactions may be comparable in these systems, which should lead to the implementation of new states and properties. Specific features of
the properties of low-dimensional systems, such as chains and lattice nanostructures, are due to their discreteness. It is important for the practical use of these structures that the parameters of an individual nanoparticle and the interaction energy between nanoparticles can be varied in a wide range and that the equilibrium configurations of the systems can be controlled by an external magnetic field. As applied to these problems, methods of computer experiment have become very popular, which make it possible t
Data Loading...
