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Related papers: Paramagnetic alignment of fractal grains

200 papers

Barnett relaxation, first described by Purcell in 1979, appears to play a major role in the alignment of grains with the interstellar magnetic field. In 1999, Lazarian and Draine proposed that Barnett relaxation and its relative, nuclear…

Astrophysics of Galaxies · Physics 2017-08-16 Erald Kolasi , Joseph C. Weingartner

The dynamical mechanisms underlying the grain evolution and growth are of fundamental importance in controlling the structural properties of large-scale polycrystalline materials, but the effects of lattice ordering and distinct atomic…

Materials Science · Physics 2022-01-03 Brendon Waters , Zhi-Feng Huang

Numerical simulations of assemblies of grains under cyclic loading exhibit ``granular ratcheting'': a small net deformation occurs with each cycle, leading to a linear accumulation of deformation with cycle number. We show that this is due…

Soft Condensed Matter · Physics 2009-11-13 S. McNamara , R. García-Rojo , H. J. Herrmann

Oriented attachment (OA) has become a well-recognized mechanism for the growth of metal, ceramic, and biomineral crystals. While many computational and experimental studies of OA have shown that particles can attach with some misorientation…

Materials Science · Physics 2020-04-09 Andrew P. Lange , Amit Samanta , Tammy Y. Olson , Selim Elhadj

We consider the grain growth and stagnation in polycrystalline microstructures. From the phase field crystal modelling of the coarsening dynamics, we identify a transition from a grain-growth stagnation upon deep quenching below the melting…

Materials Science · Physics 2013-09-20 Mathias Bjerre , Jens Magelund Tarp , Luiza Angheluta , Joachim Mathiesen

We apply the theory of radiative torque (RAT) alignment for studying protoplanetary disks around a T-Tauri star and perform 3D radiative transfer calculations to provide the expected maps of polarized radiation to be compared with…

Earth and Planetary Astrophysics · Physics 2017-04-19 Ryo Tazaki , Alexandre Lazarian , Hideko Nomura

This study proposes a new analytical model for grain boundary pinning by second phase particles in two-dimensional polycrystals. This approach not only considers how particles impede grain growth, but also elucidates their role in…

Materials Science · Physics 2024-04-23 Madeleine Bignon , Marc Bernacki

We examine analytically equilibrium conformations of elastic chains of paramagnetic beads in the presence of a precessing magnetic field. Conformations of these filaments are determined by minimizing their total energy, given in the…

Soft Condensed Matter · Physics 2017-11-17 Pablo Vázquez-Montejo , Joshua M. Dempster , Mónica Olvera de la Cruz

Small superconducting grains are discussed in the frameworks of both the reduced BCS Hamiltonian and the Universal Hamiltonian. It is shown that fluctuations of electrons in levels far from the Fermi energy dominate superconducting…

Mesoscale and Nanoscale Physics · Physics 2008-06-12 Moshe Schechter

We study the alignment of irregular dust grains by mechanical torques due to the drift of grains through the ambient gas. We first calculate mechanical torques (MATs) resulting from specular reflection of gas atoms for seven irregular…

Astrophysics of Galaxies · Physics 2018-01-31 Thiem Hoang , Jungyeon Cho , A. Lazarian

Dust polarization induced by aligned grains is widely used to study magnetic fields in various environments, including star-forming regions. However, the question of to what optical depth grain alignment still exists in a dense molecular…

Astrophysics of Galaxies · Physics 2021-03-03 Thiem Hoang , Le Ngoc Tram , Hyeseung Lee , Pham Ngoc Diep , Nguyen Bich Ngoc

We study the role of grain size in the rheological behaviour of calcite aggregates in the semi-brittle regime. We conduct triaxial deformation tests on three rocks, Solnhofen limestone, Carrara marble and Wombeyan marble, with average grain…

Geophysics · Physics 2024-03-13 Christopher Harbord , Nicolas Brantut , David Wallis

The ability to use external magnetic fields to influence the microstructure in polycrystalline materials has potential applications in microstructural engineering. To explore this potential and to understand the complex interactions between…

Materials Science · Physics 2019-04-03 R. Backofen , K. R. Elder , A. Voigt

Exchange coupling between magnetic grains is essential for maintaining the stability of stored information in magnetic recording media. Using an atomistic spin model, we have investigated the coupling between neighbouring magnetic grains…

In established theories of grain coarsening, grains disappear either by shrinking or by rotating as a rigid object to coalesce with an adjacent grain. Here we report a third mechanism for grain coarsening, in which a grain splits apart into…

A theory is presented for the statistics of the excitation spectrum of a disordered metal grain in contact with a superconductor. A magnetic field is applied to fully break time-reversal symmetry in the grain. Still, an excitation gap of…

Condensed Matter · Physics 2007-05-23 K. M. Frahm , P. W. Brouwer , J. A. Melsen , C. W. J. Beenakker

Recent experiments have highlighted the intrinsic magnetic anisotropy in coil-coil diblock copolymers, specifically in poly(styrene-b-4-vinylpyridine) (PS-b-P4VP), that enables magnetic field alignment at field strengths of a few tesla. We…

The radiative torque (RAT) mechanism is the most promising way of explaining observed polarization arising from aligned grains. We explore the efficiency of the grain alignment by an anisotropic radiation flow for an extensive ensemble of…

Astrophysics of Galaxies · Physics 2019-06-26 Joonas Herranen , Alex Lazarian , Thiem Hoang

We consider a model of the dynamics of a magnetic grain, incorporating interactions with nuclear and paramagnetic spins, conduction electrons, and phonons. Decoherence comes both from the spins and the electrons, although electron effects…

Condensed Matter · Physics 2007-05-23 N. V. Prokof'ev , P. C. E. Stamp

The size of dust grains, $a$, is key to the physical and chemical processes in circumstellar disks, but observational constraints of grain size remain challenging. (Sub)millimeter continuum observations often show a percent-level…