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Topic: Magnetic ordering


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In the News (Thu 18 Apr 19)

  
  Other  Magnetic Materials
As mentioned previously, the saturation magnetisation of a material decreases on heating towards the Curie temperature due to a decrease in the degree of alignment of the atomic magnetic moments.
If the magnetic bias was not present then a current in either direction would cause the actuator to expand and if the actuator was being used as a loud speaker then the frequency of voltage applied to the coil would be doubled by the speaker.
Under the influence a magnetic field the relative orientation of the magnetisation of the layers changes and the electrical resistance decreases to a minimum when the magnetisation directions of the layers are parallel.
www.aacg.bham.ac.uk /magnetic_materials/other_mag_materials.htm   (620 words)

  
 Magnetism - Wikipedia, the free encyclopedia
Normally, magnetic fields are seen as dipoles, having a "South pole" and a "North pole"; terms dating back to the use of magnets as compasses, interacting with the Earth's magnetic field to indicate North and South on the globe.
Alnico magnets are made by casting or sintering a combination of aluminium, nickel and cobalt with iron and small amounts of other elements added to enhance the properties of the magnet.
Flexible magnets are similar to injection molded magnets, using a flexible resin or binder such as vinyl, and produced in flat strips or sheets.
en.wikipedia.org /wiki/Magnetism   (2092 words)

  
 Magnetic Order in Superconductors
The effects of magnetic impurities and the possibility of magnetic ordering in superconductors has had a rich and interesting history, and we have had a longstanding interest in investigating such systems.
Observation of Oscillatory Magnetic Order in the Reentrant Antiferromagnetic Superconductor HoNi
Antiferromagnetic Order of the Ru and Gd in Superconducting RuSr
www.ncnr.nist.gov /staff/jeff/magnetic_order_in_superconductor.html   (1719 words)

  
 Physics News Update
In the Leipzig experiment, the protons were supplied by a nearby accelerator, and their presence in the sample in small amounts was just enough to inspire a small magnetic ordering among the carbon atoms.
The magnetism was then measured by sensitive SQUID detectors and magnetic force microscopy at the surface.
Weak magnetism in graphite might also have implications for the study of biomolecules, which are rich in carbon-hydrogen bonds, or for astronomy since space is rich in carbon-filled gas clouds undergoing irradiation.
www.aip.org /enews/physnews/2003/split/663-2.html   (195 words)

  
 PASPS III Conference: Poster Session
In general, it has been reported that the magnetic ordering in the diluted magnetic system could be induced by the carrier.
However, we could induce the ferromagnetic ordering through the additional doping of Li into (Zn, Cr)O.[1] In order to investigate the formation of the secondary phase contributing to the ferromagnetism, we employed the neutron diffraction for powder sample and magnetic force microscope (MFM) for thin film.
This decreasing of carrier concentration and eliminating of magnetism could be explained by the electronic structure calculated by the first principle calculation.
www.sainc.com /pasps3/agendaposterView.asp?paperID=77   (307 words)

  
 Organic-Based Magnets: A New Frontier   (Site not responding. Last check: 2007-10-14)
In 1986, they discovered the first organic material to become magnetically ordered (at very low temperature, -268 degrees C / -441 degrees F), demonstrating for the first time that a magnet could be made using organic chemistry and without the usual high temperature, energy intensive processing.
(Magnetic ordering refers to the orientation of each atoms' electron spins, which behave like tiny magnets; when many adjacent electron spins align in the same direction, the material can be a strong magnet.) Miller and Epstein's compound is composed of molecular units.
Enhancement of the Magnetic Ordering Temperature (and Air Stability) of a Mixed Valent Vanadium Hexacyanochromate(III) Magnet to 99 C (372 K), O. Hatlevik, W. Buschmann, J. Zhang, J. Manson, J. Miller, Adv.
www.er.doe.gov /Sub/Accomplishments/Decades_Discovery/16.html   (518 words)

  
 APS - 2005 APS March Meeting - Event - Tuning of Magnetic Ordering in Single-Molecule Magnets   (Site not responding. Last check: 2007-10-14)
Single-molecule magnets (SMMs) are usually characterized by superparamagnetic blocking of the cluster spins.
Magnetic interactions between cluster spins may, however, drive to long- range order when the cluster magnetic anisotropy is sufficiently small.
Antiferromagnetic long-range order at $T_{N}=0.8$~K is found for $R\bar{3}$ symmetry, whereas any sign of ordering is wiped out for $Pa\bar{3}$ symmetry leaving a superparamagnetic blocking at $T_{B}\simeq 0.5$~K as the prevailing mechanism.
meetings.aps.org /Meeting/MAR05/Event/26063   (162 words)

  
 Magnetic ordering of TiFe2   (Site not responding. Last check: 2007-10-14)
The positions of the magnetic peaks observed in both the powder and single-crystal diffraction measurements put severe constrain on the possible magnetic structures.
Firstly the magnetic cell is the same as the crystallographic one hence the magnetic propagation vector k=(0, 0, 0,).
On the other hand, the magnetic scattering by the magnetization induced by the applied field field in the polarized neutron diffraction experiment was compared with that calculated for a simple model consisting of superposition of spherical magnetization distributions as calculated for the Fe²+ free ion centred at the iron sites.
www.ill.fr /YellowBook/D15/EDIT94/d3-d15_exp1.html   (455 words)

  
 ID20 Magnetic Scattering Beamline — ESRF   (Site not responding. Last check: 2007-10-14)
The very recent developments in coherent magnetic scattering, orbital ordering and magnetic surface experiments by the scientists of this beamline are just a few examples.
X-ray magnetic scattering complement the magnetic neutron scattering technique regarding sample size, Q-resolution, single magnetic domain studies, separation of angular and spin contributions to the magnetic moment, and magnetic ordering of non-suitable, highly neutron absorbing, compounds.
Large resonant enhancements of the scattering cross section may be observed when the incident photon energy is tuned close to an atomic absorption edge, e.g., the M4,5 edges of actinides, the L2,3 edges of rare earths, or the K edges of transition metals.
www.esrf.fr /UsersAndScience/Experiments/XASMS/ID20   (478 words)

  
 Magnetic Shield Corp. - Newsletter - Vol. 2, Num. 2
Unlike magnetic shields that use their high permeability to attract magnetic fields, RF shielding has little or no magnetic permeability.
The attenuation of a magnetic shield is the ratio of the measured magnetic field before shielding to the field measured after shielding is applied.
Magnetic Shield is going all out to be Your Preferred Source for solving magnetic interference problems and eliminating CRT monitor interference.
www.magnetic-shield.com /newsletter/vol2-2/p3.html   (472 words)

  
 Classes of Magnetic Materials
The spontaneous magnetization is the net magnetization that exists inside a uniformly magnetized microscopic volume in the absence of a field.
This behavior is called hysteresis and a plot of the variation of magnetization with magnetic field is called a hysteresis loop.
In ferrimagnets, the magnetic moments of the A and B sublattices are not equal and result in a net magnetic moment.
www.geo.umn.edu /orgs/irm/hg2m/hg2m_b/hg2m_b.html   (1459 words)

  
 Ferromagnetism - Wikipedia, the free encyclopedia
More recently, however, different classes of spontaneous magnetization have been identified when there is more than one magnetic ion per primitive cell of the material, leading to a stricter definition of "ferromagnetism" that is often used to distinguish it from ferrimagnetism.
The transition between two domains, where the magnetization flips, is called a Domain wall (e.g., a Bloch/Néel wall, depending upon whether the magnetization rotates parallel/perpendicular to the domain interface) and is a gradual transition on the atomic scale (covering a distance of about 300 ions for iron).
This magnetization as a function of the external field is described by a hysteresis curve.
en.wikipedia.org /wiki/Ferromagnetism   (1295 words)

  
 Session Y22 - Magnetic Nanostructures XII: Molecular Magnets.
The organometallic ring molecules Fe_6 and Fe_10 are leading examples of a class of nanoscopic molecular magnets, which have been of intense recent interest both for their intrinsic magnetic properties and as candidates for the observation of macroscopic quantum coherent phenomena.
Magnetic measurements revealed an antiferromagnetic coupling between outer Mn ions with a weaker coupling to the central Mn ion leading to a S=5/2 ground state.
Based on the temperature and magnetic field dependences of the spectra as well as a comparison with the neutron scattering data, we speculate that this mode may involve the motion of Mn(3) atoms in the crown.
flux.aps.org /meetings/YR01/MAR01/abs/S8720.html   (2566 words)

  
 The extraordinry properties of magnetic oxides
In these materials, orbital-charge ordering can be destroed by doping the manganese sites with magnetic cations such as chromium or ruthenium, which by magnetic coupling with adjacent manganese induce ferromagnetism and metallicity, so that spectacular modifications of the magnetic phase diagrams of these systes are obtained.
The curious effect of thermal cycling upon the resistivity, and the step like behavior at low temperature of their magnetization, resistivit and specific heat versus magnetic field at low temperature, are also certainly related to the phase separation that exists in these compounds, and suggest a martensitic type mechanism.
Such a coupling of the magnetic and transport properties in the cobalttes is not limited to the oxygen deficient perovskite structure.
www.europhysicsnews.com /full/24/article12/article12.html   (1814 words)

  
 Hidekazu Tanaka (Tokyo Institute of Technology), Magnetic Quantum Phase Transitions in Coupled Spin Dimer Systems
Their magnetic ground states are spin singlets with excitation gaps D/ kB of 7.5 K and 31 K, respectively.
In a magnetic field, created Sz=+1 comp onent of spin triplet which has recently been called triplon can hop to neig hboring dimers and interact with one another due to the transverse and longi tudinal components of the interdimer interaction.
When the hopping term is dominant, triplons can undergo Bose-Einstein condensation in a magnetic f ield higher than the critical field Hc corresponding to the gap D. This lead s to field-induced transverse magnetic ordering.
online.itp.ucsb.edu /online/exotic_c04/tanaka   (257 words)

  
 MAGNETiC Therapy - Ordering
If out of stock you will be notified of how long it will take to produce and send out your order.
The Elegance range of jewellery are handmade in the UK and whilst the majority of sizes are always in stock certain sizes will have to be made to order.
Overseas orders delivered at current postal rates at that time.
www.magnetic.uk.com /ordering.shtml   (158 words)

  
 Magnetic car signs by SignsByWeb. Discount magnetic signs for cars and trucks. magnet, car signs...
Our magnetic signs are perfect for temporary or permanent car signs or truck signs and vehicle identification.
The magnetic sign sheeting is the thickest available, it will not blow off your vehicle.
Ordering can be done either via faxing in order, mailing in order or calling in your order.
www.cotteradvertising.com /magneticsigns.html   (422 words)

  
 National Synchrotron Light Source
This method promises to lead to a better understanding of magnetism in magnetic oxides and to assist in improving theoretical models of correlated electron systems.
By examining the changes in the pre-edge spectra for temperatures above and below magnetic ordering temperature, we have developed an electron excitation model to understand the origin of the features a1, a2 and a3.
Our model and SPXANES measurements could also be used to predict magnetic ordering changes in materials such as thin films, single crystal or powders.
www.nsls.bnl.gov /newsroom/science/2002/09-Tyson.htm   (683 words)

  
 Dilute Magnetic GaN, SiC and Related Semiconductors
  Since the magnetic properties of ferromagnetic semiconductors are a function of carrier concentration in the material in many cases, then it will be possible to have electrically or optically-controlled magnetism through field-gating of transistor structures or optical excitation to alter the carrier density.
In this review we focus on a particular and emerging aspect of spintronics, namely recent developments in achieving practical magnetic ordering temperatures in technologically useful semiconductors[73-79].While the progress in synthesizing and controlling the magnetic properties of III-arsenide semiconductors has been astounding, the reported Curie temperatures are too low to have significant practical impact.
  The apparent ordering temperature is ~ 250 K at this dose(again based on where the magnetization goes to zero within experimental error), while the samples implanted at the lower dose remained paramagnetic.
mse.ufl.edu /~spear/recent_papers/Dilute_Mag_GaN/Dilute_Mag_GaN.htm   (8123 words)

  
 Department of Physics | West Virginia University
However the nature of magnetism in different materials depends on the arrangement of electrons in the material and how these electron interact among themselves and with their environment.
This leads to different kinds of magnetism (paramagne-tism, superparamagnetism, diamagnetism, ferromagnetism, antiferromagnetism, ferrimag-netism, spin glasses, etc.) with varying values of the magnetic ordering temperatures.
At WVU, we are investigating high temperature superconductors as well as a variety of magnetic materials including nanoscale magnetic particles, thin films of ferrites and oxides, multilayer systems, intermetallics, and superalloys of nickel.
www.wvu.edu /~physics/condensedmatter/magnetic.htm   (238 words)

  
 Souchkov
is a representative of a group of multiferroic materials where ferroelectricity is induced by spiral magnetic ordering at low temperatures.
These materials demonstrate several weak structural and magnetic transitions reflecting complex interplay between magnetic order and the lattice.
The coupling between ferroelectric and magnetic order parameters in multiferroics opens the possibility to manipulate electric properties through magnetic fields and vice versa which, in turn, gives these materials potential for applications in spintronics and as read/write heads.
www.physics.umd.edu /cmo/people/andrei/Souchkov.htm   (557 words)

  
 Pre-History of Magnetic Neutron Scattering
Prior to the development of neutron scattering techniques, the only known magnetic ordering of materials without current flowing in them was ferromagnetism, because of its strong bulk effects.
The discovery of antiferromagnetism had to wait for magnetic neutron diffraction.
Néel first suggested the possibility of antiferromagnetic ordering of magnetic moments in solids in 1930.
www.vsu.edu /pages/490.asp   (388 words)

  
 magnetic materials
By measuring the magnetic, thermal, and thermal transport properties of some very new materials, we try to characterize the nature of their magnetic ground states.
We found a phase transition associated with magnetic ordering at low temperature.
Interestingly, the entropy-per-mole associated with the transition is less than 10 % of Rln2, indicating that much of the spin degeneracy has already been lifted by the 2D Heisenberg couplings at higher temperatures.
www.cas.muohio.edu /~clayhoja/magnetic.htm   (456 words)

  
 Magnetic Signs - removeable car magnets
Our 100% vehicle magnetic signs are highly durable and are a cost-effective way to promote name recognition within your business area.
Magnetic signs with your graphics, photo, or logo.
When experience counts, go with a sign maker that has been a trusted producer of magnetic signs for seventeen years.
www.magneticsignsontime.com   (220 words)

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