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By numerically solving the equations of motion for atomic spins we show that internal spin-wave processes in large enough magnetic particles, initially in unstable states, lead to complete magnetization reversal and thermalization. The…

Other Condensed Matter · Physics 2012-01-10 D. A. Garanin , H. Kachkachi

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…

We consider a particle coupled to a dissipative environment and derive a perturbative formula for the dephasing rate based on the purity of the reduced probability matrix. We apply this formula to the problem of a particle on a ring, that…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Doron Cohen , Baruch Horovitz

On the basis of the mean spherical approximation of multicomponent dipolar hard sphere mixtures an analytical expression is proposed for the magnetic field dependence of the magnetization of size polydisperse ferrofluids. The polydispersity…

Soft Condensed Matter · Physics 2013-07-18 I. Szalai , S. Nagy , S. Dietrich

We report on the use of magnetic sedimentation as a means to determine the size distribution of dispersed magnetic particles. The particles investigated here are i) single anionic and cationic nanoparticles of diameter D = 7 nm and ii)…

Soft Condensed Matter · Physics 2007-09-10 J. -F. Berret , O. Sandre , A. Mauger

A self-consistent mean-field theory explaining the thermal remagnetization (TR) of polycrystalline permanent magnets is given. The influence of the environment of a grain is treated by an inclusion approximation, relating the field inside…

Materials Science · Physics 2009-11-07 R. Schumann , L. Jahn

The complex permittivity and permeability of superparamagnetic iron-oxide nanoparticles has been quantified using a circular waveguide assembly with a static magnetic field to align the nanoparticle's magnetization. The high sensitivity of…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 B. M. Yao , Y. S. Gui , M. Worden , T. Hegmann , M. Xing , X. S. Chen , W. Lu , Y. Wroczynskyj , J. van Lierop , C. -M. Hu

The magnetic moment of the proton is calculated using a geometric unified theory. The geometry determines a generalized Pauli equation showing anomalous terms due to the triplet proton structure. The theoretical result gives a bare…

General Physics · Physics 2007-05-23 Gustavo R. Gonzalez-Martin , Ignacio J. Taboada , Javier G. Gonzalez

Effective demagnetizing factors that connect the sample magnetic moment with the applied magnetic field are calculated numerically for perfectly diamagnetic samples of various non-ellipsoidal shapes. The procedure is based on calculating…

Superconductivity · Physics 2018-08-01 R. Prozorov , V. G. Kogan

A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 O. Prus , Y. Yaish , M. Reznikov , U. Sivan , V. Pudalov

Implementations of the Bruggeman and Maxwell Garnett homogenization formalisms were developed to estimate the relative permittivity dyadic of a homogenized composite material (HCM), namely $\underline{\underline{\epsilon}}^{\rm HCM}$,…

Optics · Physics 2025-04-07 Héctor M. Iga-Buitrón , Tom G. Mackay , Akhlesh Lakhtakia

We have investigated the magnetic properties of carbon powders which consist of nanodisks, nanocones, and a small fraction of carbon-black particles. Magnetization measurements were carried out using a superconducting quantum interference…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 Jozef Cernak , Geir Helgesen , Jozef Kovac , Arne T. Skjeltorp , Josef Voltr

When modeling the density and grain size distribution in debris disks, the minimum particle size is often significantly larger than the corresponding blowout size. While the dust particles are usually modeled as compact, homogenous spheres,…

Solar and Stellar Astrophysics · Physics 2013-02-22 Florian Kirchschlager , Sebastian Wolf

Saturated random packing of particles built of two identical, relatively shifted spheres in two and three dimensional flat and homogeneous space was studied numerically using random sequential adsorption algorithm. The shift between centers…

Materials Science · Physics 2015-06-19 Michał Cieśla

Polarization at millimeter wavelengths provides a powerful diagnostic of dust grain properties in protoplanetary disks. Standard models based on solid spherical grains often struggle to reproduce the observed polarization fractions and…

We present the data on depolarization of polarized neutron beam and second harmonic of magnetization ($M_2$) for Nd$_{1-x}$Ba$_x$MnO$_3$ ($x$ = 0.23, the Curie temperature $T_C \approx$ 124 K; $x$ = 0.25, $T_C \approx$ 129 K) manganites.…

Mesoscale and Nanoscale Physics · Physics 2009-11-24 A. V. Lazuta , V. A. Ryzhov , V. V. Runov , I. O. Troyanchuk

Magnetization reversal of individual, isolated high-aspect-ratio Fe nanoparticles with diameters comparable to the magnetic exchange length is studied by high-sensitivity submicron Hall magnetometry. For a Fe nanoparticle with diameter of 5…

Materials Science · Physics 2009-11-11 Yongqing Li , Peng Xiong , Stephan von Molnar , Yuzo Ohno , Hideo Ohno

At high densities fluids of strongly dipolar spherical particles exhibit spontaneous long-ranged orientational order. Typically, due to demagnetization effects induced by the long range of the dipolar interactions, the magnetization…

Soft Condensed Matter · Physics 2009-10-30 B. Groh , S. Dietrich

In extracting deformation parameters from multipole moments for deformed nuclei, one commonly uses the formulas which are based on a sharp-cut density distribution. We discuss a possible ambiguity for this procedure and clarify the role of…

Nuclear Theory · Physics 2009-11-11 K. Hagino , N. W. Lwin , M. Yamagami

An interferometric imaging technique has been proposed to instantly measure the diameter of individual spherical dust particles suspended in a gas discharge plasma. The technique is based on the defocused image analysis of both spherical…

Plasma Physics · Physics 2016-04-06 M. Chaudhuri , V. Nosenko , H. M. Thomas