A STUDY OF 2D ISING FERROMAGNETS WITH DIPOLE INTERACTIONS

2001 ◽  
Vol 15 (21) ◽  
pp. 895-903 ◽  
Author(s):  
M. IFTI ◽  
Q. LI ◽  
C. M. SOUKOULIS ◽  
M. J. VELGAKIS
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Domain Walls ◽  
Magnetic Films ◽  
Local Magnetic Field ◽  
Dipolar Interactions ◽  
Dipole Interactions ◽  
Ising Ferromagnets ◽  
Transition Points ◽  
Striped Phases

A two-dimensional Ising model with competing short range ferromagnetic and long range dipolar interactions is used to study the transition properties and phase diagram in ultrathin magnetic films. Monte Carlo simulations in systems with exchange and dipolar interactions reveal a ground state of striped phases with varying width. By raising the temperature, the domain walls are smeared out by fluctuations, leading to a random domain mesoscopic phase with no long-range order, and finally the domains are melted to the high-temperature disordered phase. Local magnetic field distributions and specific heat calculations reproduced transition points consistent with the previous phase diagram of the model. The resemblance to the phase diagram in ultrathin magnetic films, such as in Fe/Cu(100), is discussed.

scholarly journals Origin of spin-ice behavior in Ising pyrochlore magnets with long-range dipole interactions: an insight from mean-field theory

2001 ◽  
Vol 79 (11-12) ◽  
pp. 1339-1351 ◽  
Author(s):  
M JP Gingras ◽  
B C den Hertog
Keyword(s):  
Long Range ◽  
Nearest Neighbor ◽  
Mean Field Theory ◽  
Mean Field ◽  
Field Analysis ◽  
Dipolar Interactions ◽  
Spin Ice ◽  
Qualitative Properties ◽  
Dipole Interactions ◽  
Long Range Interactions

Recent experiments suggest that the Ising pyrochlore magnets Ho2Ti2O7 and Dy2Ti2O7 display qualitative properties of the ferromagnetic nearest-neighbor spin-ice model proposed by Harris et al. Phys. Rev. Lett. 79, 2554 (1997). The manifestation of spin-ice behavior in these systems despite the energetic constraints introduced by the strength and the long-range nature of dipole–dipole interactions, remains difficult to understand. We report here results from a mean-field analysis that shed some light on the origin of spin-ice behavior in (111) Ising pyrochlores. Specifically, we find that there exist a large frustrating effect of the dipolar interactions beyond the nearest neighbor, and that the degeneracy established by effective ferromagnetic nearest-neighbor interactions is only very weakly lifted by the long-range interactions. Such behavior only appears beyond a cut-off distance corresponding to O(102) nearest neighbor. Our mean-field analysis shows that truncation of dipolar interactions leads to spurious ordering phenomena that change with the truncation cut-off distance. PACS Nos.: 75.10-b, 75.10Hk, 75.20-g, 75.30-m

Phase diagram of the one-dimensional t-J model with long-range dipolar interactions

2015 ◽  
Vol 110 (3) ◽  
pp. 37002 ◽  
Author(s):  
Chen Cheng ◽  
Bin-Bin Mao ◽  
Fu-Zhou Chen ◽  
Hong-Gang Luo
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Dipolar Interactions ◽  
One Dimensional ◽  
The One

Nucleati on on domain walls near singular phase diagram points

1990 ◽  
Vol 111 (1) ◽  
pp. 111-115 ◽  
Author(s):  
A. A. Bulbich ◽  
P. E. Pumpjan
Keyword(s):  
Phase Diagram ◽  
Domain Walls

scholarly journals Quasi-1D XY antiferromagnet Sr2Ni(SeO3)2Cl2 at Sakai-Takahashi phase diagram

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Kozlyakova ◽  
A. V. Moskin ◽  
P. S. Berdonosov ◽  
V. V. Gapontsev ◽  
S. V. Streltsov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Density Functional ◽  
Uniaxial Anisotropy ◽  
Exchange Interactions ◽  
Spin Liquid ◽  
Functional Theory ◽  
One Dimensional ◽  
Ordered Phases ◽  
Experimental Findings

AbstractUniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr2Ni(SeO3)2Cl2, is a spin-1 chain system which passes through a correlations regime at Tmax ~ 12 K to long-range order at TN = 6 K. Under external magnetic field it experiences the sequence of spin-flop at Bc1 = 9.0 T and spin-flip transitions Bc2 = 23.7 T prior to full saturation at Bsat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.

scholarly journals Mobile and immobile boundaries in ferroelectric films

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Yudin ◽  
K. Shapovalov ◽  
T. Sluka ◽  
J. Peräntie ◽  
H. Jantunen ◽  
...  
Keyword(s):  
Long Range ◽  
Domain Walls ◽  
Ferroelectric Properties ◽  
Practical Importance ◽  
Dynamic Responses ◽  
Ferroelectric Films ◽  
Domain Structures ◽  
Mobile Interfaces ◽  
Ferroelastic Domains ◽  
Viable Method

AbstractThe intrinsic mobile interfaces in ferroelectrics—the domain walls can drive and enhance diverse ferroelectric properties, essential for modern applications. Control over the motion of domain walls is of high practical importance. Here we analyse theoretically and show experimentally epitaxial ferroelectric films, where mobile domain walls coexist and interact with immobile growth-induced interfaces—columnar boundaries. Whereas these boundaries do not disturb the long-range crystal order, they affect the behaviour of domain walls in a peculiar selective manner. The columnar boundaries substantially modify the behaviour of non-ferroelastic domains walls, but have negligible impact on the ferroelastic ones. The results suggest that introduction of immobile boundaries into ferroelectric films is a viable method to modify domain structures and dynamic responses at nano-scale that may serve to functionalization of a broader range of ferroelectric films where columnar boundaries naturally appear as a result of the 3D growth.

Long-range strains and the effects of applied field at 180° ferroelectric domain walls in lithium niobate

2004 ◽  
Vol 69 (6) ◽  
Author(s):  
Terrence Jach ◽  
Sungwon Kim ◽  
Venkatraman Gopalan ◽  
Stephen Durbin ◽  
David Bright
Keyword(s):  
Lithium Niobate ◽  
Long Range ◽  
Applied Field ◽  
Domain Walls ◽  
Ferroelectric Domain

scholarly journals Striped phases in the two-dimensional Hubbard model with long-range Coulomb interaction

1998 ◽  
Vol 58 (20) ◽  
pp. 13506-13509 ◽  
Author(s):  
G. Seibold ◽  
C. Castellani ◽  
C. Di Castro ◽  
M. Grilli
Keyword(s):  
Hubbard Model ◽  
Long Range ◽  
Coulomb Interaction ◽  
Two Dimensional ◽  
Striped Phases

scholarly journals Configurational Statistics

1978 ◽  
Vol 21 (85) ◽  
pp. 73-83 ◽  
Author(s):  
J. F. Nagle
Keyword(s):  
Dielectric Constant ◽  
Long Range ◽  
Short Range ◽  
Theoretical Calculations ◽  
Correlation Factor ◽  
Residual Entropy ◽  
Dipolar Interactions ◽  
Computational Tool ◽  
Kirkwood Correlation Factor ◽  
Polarization Factor

Abstract Theories of the dielectric constant in ice differ in three fundamentally different ways that are often confused with each other. First, there is the choice of interactions to include in the model, notably whether to try to include long-range dipolar interactions as in the Kirkwood theory or to include only the short-range ice-rule interactions. Second, there is the choice of the kind of statistical quantity calculated, e.g. the Kirkwood correlation factor g or the polarization factor G, which Stillinger and Cotter showed to be different. Finally, there is the choice of the kind of computational tool used, and in original papers this choice often obscures the first two differences. With these distinctions in mind a review is given of current theoretical calculations of the dielectric constant and the residual entropy and how the different theories relate to each other and to experiments.

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