Ground State and Magnetostatic Properties of a Dipole System Arranged in Two-Dimensional Lattice

Bolcal, E.; Dimitrov, V. I.; Aktaş, B.; Aslan, H.; Bozkurt, Ayhan

doi:10.12693/aphyspola.121.257

Cited by 5 publications

(5 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given the NC volume V , this FM-like behavior points to a rather large magnitude of K or to a significant role played by spin-dependent interactions between the NCs (Hai et al, 2007). For specific spatial distributions and densities of FM nanoparticles, long-range dipole interactions and/or exchange coupling lead to the so-called superferromagnetic phase (Bolcal et al, 2012;Mørup et al, 2010;Panov, 2012), whose characteristics are consistent with the data displayed in Fig. 17(b).…”

Section: B Magnetic Propertiessupporting

confidence: 79%

Spinodal nanodecomposition in semiconductors doped with transition metals

et al. 2015

View full text Add to dashboard Cite

This review presents the recent progress in computational materials design, experimental realization, and control methods of spinodal nanodecomposition under three-and two-dimensional crystal-growth conditions in spintronic materials, such as magnetically doped semiconductors. The computational description of nanodecomposition, performed by combining first-principles calculations with kinetic Monte Carlo simulations, is discussed together with extensive electron microscopy, synchrotron radiation, scanning probe, and ion beam methods that have been employed to visualize binodal and spinodal nanodecomposition (chemical phase separation) as well as nanoprecipitation (crystallographic phase separation) in a range of semiconductor compounds with a concentration of transition metal (TM) impurities beyond the solubility limit. The role of growth conditions, codoping by shallow impurities, kinetic barriers, and surface reactions in controlling the aggregation of magnetic cations is highlighted. According to theoretical simulations and experimental results the TM-rich regions appear in the form of either nanodots (the dairiseki phase) or nanocolumns (the konbu phase) buried in the host semiconductor. Particular attention is paid to Mn-doped group III arsenides and antimonides, TM-doped group III nitrides, Mn-and Fe-doped Ge, and Cr-doped group II chalcogenides, in which ferromagnetic features persisting up to above room temperature correlate with the presence of nanodecomposition and account for the application-relevant magnetooptical and magnetotransport properties of these compounds. Finally, it is pointed out that spinodal nanodecomposition can be viewed as a new class of bottom-up approach to nanofabrication.

show abstract

Section: B Magnetic Propertiessupporting

confidence: 79%

Spinodal nanodecomposition in semiconductors doped with transition metals

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Instead, as they are set during the buildup of the layer they get correlated with the dipolar interactions which are already there. In other words, the final pattern contains an imprint of the dipolar forces and so additionally favors their ferromagnetic arrangement, most likely in a domainlike fashion, 95,96 accounting for vanishing coercivity and remanence, and so leading to fast saturation due to a swift domain rotations and domain walls annihilation in an external field. Interestingly, a qualitatively similar explanation was already put forward by Straumal and co-workers who also assigned the FM features of DMO to 2D-like structure(s) within the material: first to the grain boundaries in general, 97 but narrowed their view later to specific textures only.…”

Section: Interfacial Ferromagnetismmentioning

confidence: 99%

Homogeneous and heterogeneous magnetism in (Zn,Co)O: From a random antiferromagnet to a dipolar superferromagnet by changing the growth temperature

et al. 2013

View full text Add to dashboard Cite

A series of (Zn,Co)O layers with Co contents x up to 40% grown by atomic layer deposition have been investigated. All structures deposited at 160 • C show magnetic properties specific to II-VI dilute magnetic semiconductors with localized spins S = 3/2 coupled by strong but short-range antiferromagnetic interactions resulting in low-temperature spin-glass freezing for x = 0.16 and 0.4. At higher growth temperature (200 • C) metallic Co nanocrystals precipitate in two locations giving rise to two different magnetic responses: (i) a superparamagnetic contribution coming from volume disperse nanocrystals; (ii) a ferromagneticlike behavior brought about by nanocrystals residing at the (Zn,Co)O/substrate interface. It is shown that the dipolar coupling within the interfacial two-dimensional dense dispersion of nanocrystals is responsible for the ferromagneticlike behavior.

show abstract

“…5 The magnetic structures of two-dimensional (2D) Bravais spin lattices induced by magnetic dipole interactions have also been investigated. [6][7][8][9][10] Luttinger and Tisza also showed that in a classical cubic dipolar AFM in the magnetically-ordered state at temperature T = 0 with a magnetic field H z applied perpendicular to the easy axis of ordering, the component µ z of the ordered moment per spin in the direction of H z is proportional to H z for 0 ≤ H z ≤ H c and is equal to the saturation moment µ sat for H z > H c , where H c is termed the critical field. 4 An expression for the magnetic susceptibility χ z = µ z /H z for 0 ≤ H z ≤ H c was given.…”

Section: Introductionmentioning

confidence: 99%

Magnetic dipole interactions in crystals

Johnston

2016

Phys. Rev. B

View full text Add to dashboard Cite

The influence of magnetic dipole interactions (MDIs) on the magnetic properties of local-moment Heisenberg spin systems is investigated. A general formulation is presented for calculating the eigenvalues λ and eigenvectorsμ of the MDI tensor of the magnetic dipoles in a line (one dimension 1D), within a circle (2D) or sphere (3D) of radius r surrounding a given moment µi for given magnetic propagation vectors k for collinear and coplanar noncollinear magnetic structures on both Bravais and non-Bravais spin lattices. Results are calculated for collinear ordering on 1D chains, 2D square and simple-hexagonal (triangular) Bravais lattices, 2D honeycomb and kagomé non-Bravais lattices and 3D cubic Bravais lattices. The λ andμ values are compared with previously reported results. Calculations for collinear ordering on 3D simple tetragonal, body-centered tetragonal, and stacked triangular and honeycomb lattices are presented for c/a ratios from 0.5 to 3 in both graphical and tabular form to facilitate comparison of experimentally determined easy axes of ordering on these Bravais lattices with the predictions for MDIs. Comparisons with the easy axes measured for several illustrative collinear antiferromagnets (AFMs) are given. The calculations are extended to the cycloidal noncollinear 120• AFM ordering on the triangular lattice where λ is found to be the same as for collinear AFM ordering with the same k. The angular orientation of the ordered moments in the noncollinear coplanar AFM structure of GdB4 with a distorted stacked 3D ShastrySutherland spin-lattice geometry is calculated and found to be in disagreement with experimental observations, indicating the presence of another source of anisotropy. Similar calculations for the undistorted 2D and stacked 3D Shastry-Sutherland lattices are reported. The thermodynamics of dipolar magnets are calculated using the Weiss molecular field theory (MFT) for quantum spins, including the magnetic transition temperature Tm and the ordered moment, magnetic heat capacity and anisotropic magnetic susceptibility χ versus temperature T . The anisotropic Weiss temperature θp in the Curie-Weiss law for T > Tm is calculated. A quantitative study of the competition between FM and AFM ordering on cubic Bravais lattices versus the demagnetization factor in the absence of FM domain effects is presented. The contributions of Heisenberg exchange interactions and of the MDIs to Tm and to θp are found to be additive, which simplifies analysis of experimental data. Some properties in the magnetically-ordered state versus T are presented, including the ordered moment and magnetic heat capacity, and for AFMs the dipolar anisotropy of the free energy and the perpendicular critical field. The anisotropic χ for dipolar AFMs is calculated both above and below the Néel temperature TN and the results are illustrated for a simple tetragonal lattice with c/a > 1, c/a = 1 (cubic) and c/a < 1, where a change in sign of the χ anisotropy is found at c/a = 1. Finally, following the early work of Keffer, the dip...

show abstract

Ground State and Magnetostatic Properties of a Dipole System Arranged in Two-Dimensional Lattice

Cited by 5 publications

References 9 publications

Spinodal nanodecomposition in semiconductors doped with transition metals

Spinodal nanodecomposition in semiconductors doped with transition metals

Homogeneous and heterogeneous magnetism in (Zn,Co)O: From a random antiferromagnet to a dipolar superferromagnet by changing the growth temperature

Magnetic dipole interactions in crystals

Contact Info

Product

Resources

About