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We study systems of classical magnetic dipoles on simple cubic lattices with dipolar and antiferromagnetic exchange interactions. By analysis and Monte Carlo (MC) simulations, we find how the antiferromagnetic phases vary with uniaxial and…

Statistical Mechanics · Physics 2007-05-23 J. F. Fernandez , J. J. Alonso

Single crystal nematic elastomers undergo a transition from a strongly ordered phase N to an "isotropic" phase I. We show that: (a) samples produced under tension by the Finkelmann procedure are intrinsically anisotropic and should show a…

Soft Condensed Matter · Physics 2009-11-10 Pierre-Gilles de Gennes , Ko Okumura

Ultracold dipolar Fermi gases represent relatively unexplored, strongly correlated systems arising from long-range and anisotropic interactions. We demonstrate the possibility of a spontaneous symmetry breaking biaxial phase in these…

Other Condensed Matter · Physics 2015-05-13 Benjamin M. Fregoso , Kai Sun , Eduardo Fradkin , Benjamin L. Lev

We perform a study of domain walls in Co/Ir$_n$/Pt(111) (n = 0,1,...,6) films by a combined approach of first-principles calculations and spin dynamics simulations. We determine the tensorial exchange interactions and the magnetic…

Mesoscale and Nanoscale Physics · Physics 2017-01-04 Gy. J. Vida , E. Simon , L. Rózsa , K. Palotás , L. Szunyogh

It is well-known that in thin ferromagnetic film with a net magnetization perpendicular to the film the collinear arrangement of spins is unstable in an in-plane field $H$ smaller than its saturation value $H_c$. Existence of a stripe phase…

Strongly Correlated Electrons · Physics 2009-05-04 A. V. Syromyatnikov

Here we demonstrate that MnTe epitaxial films with zinc-blend structure and MnTe/ZnTe multilayers should show ferroelectric polarization in antiferromagnetically (AFM) ordered state and thus belong to multiferroics. Spontaneous…

Materials Science · Physics 2008-11-14 Helen V. Gomonay , Ievgeniia G. Korniienko

A combination of experiments and numerical modeling was used to study the spatial evolution of the ferromagnetic phase transition in a thin film engineered to have a smooth gradient in exchange strength. Mean-field simulations predict, and…

We discuss theoretically phase transitions in frustrated antiferromagnets with biaxial anisotropy or dipolar forces in magnetic field applied along the easy axis at $T=0$. There are well-known sequences of phase transitions upon the field…

Strongly Correlated Electrons · Physics 2019-09-04 O. I. Utesov , A. V. Syromyatnikov

The ultrafast manipulation of magnetic order due to optical excitation is governed by the intricate flow of energy and momentum between the electron, lattice and spin subsystems. While various models are commonly employed to describe these…

We study the magnetic properties of nanoscale magnetic films with large perpendicular anisotropy comparing polarization microscopy measurements on Co_28Pt_72 alloy samples based on the magneto-optical Kerr effect with Monte Carlo…

Materials Science · Physics 2009-10-30 U. Nowak , J. Heimel , T. Kleinefeld , D. Weller

We consider the effects of polydispersity on isotropic-nematic phase equilibria in thermotropic liquid crystals, using a Maier-Saupe theory with factorized interactions. A sufficient spread (approx. 50%) in the interaction strengths of the…

Soft Condensed Matter · Physics 2013-09-03 Peter Sollich

We investigated head-to-head domain walls in nanostrips of epitaxial $\mathrm{Fe}_4\mathrm{N}(001)$ thin films, displaying a fourfold magnetic anisotropy. Magnetic force microscopy and micromagnetic simulations show that the domain walls…

Recent experiments on mixed liquid crystals have highlighted the hugely significant role of ferromagnetic nanoparticle impurities in defining the nematic-smectic-A phase transition point. Structured around a Flory-Huggins free energy of…

Soft Condensed Matter · Physics 2017-05-25 Prabir K Mukherjee , Amit K Chattopadhyay

The field of active nematics has traditionally employed descriptions based on dipolar activity, with interactions that align along a single axis. However, it has been theoretically predicted that interactions with a substrate, prevalent in…

The interplay of nematic order and phase separation in solutions of semiflexible polymers in solvents of variable quality is investigated by density functional theory (DFT) and molecular dynamics (MD) simulations. We studied coarse-grained…

Soft Condensed Matter · Physics 2019-09-04 Jiarul Midya , Sergei A. Egorov , Kurt Binder , Arash Nikoubashman

Using the Lebwohl-Lasher interaction for reciprocal local alignment, we present a comprehensive phase diagram for a dry, apolar, active nematic system using its stochastic \new{off-lattice} dynamics. \new{The nematic-isotropic transition in…

Soft Condensed Matter · Physics 2024-10-08 Arpan Sinha , Debasish Chaudhuri

We analyze a model problem based on highly disparate elastic constants that we propose in order to understand corners and cusps that form on the boundary between the nematic and isotropic phases in a liquid crystal. For a bounded planar…

Analysis of PDEs · Mathematics 2018-12-03 Dmitry Golovaty , Michael Novack , Peter Sternberg , Raghavendra Venkatraman

Domain wall dynamics in ferromagnets is complicated by internal degrees of freedom of the domain walls. We develop a model of domain walls in disordered thin films with perpendicular magnetic anisotropy capturing such features, and use it…

Statistical Mechanics · Physics 2022-03-08 Audun Skaugen , Lasse Laurson

Fourth order perturbation was applied to study a small variation of the azimuthal angle of spin of fcc structured ferromagnetic thin films with two spin layers. The variation of magnetic energy and the orientation of magnetic easy axis with…

Computational Physics · Physics 2023-01-24 M. S. M. Farhan

The antiferromagnetic Heisenberg model on a stacked triangular geometry with a finite number of layers is studied using Monte Carlo methods. A topological phase transition occurs at finite temperature for all film thicknesses. Our results…

Statistical Mechanics · Physics 2009-11-10 A. Peles , B. W. Southern