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Topic: Molecular magnet


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In the News (Thu 21 Mar 19)

  
  What Is A Magnet   (Site not responding. Last check: 2007-11-05)
The power of magnetism in a magnet is at its highest at its two poles but lower at the point equi-distant from the two poles.
The strength of a magnet or its magnetic field is measured by an instrument called gauss meter in gauss units or oersted.
On the contrary, earth’s magnetic north pole is somewhere near its geographical south pole and its magnetic south pole is in the neighborhood of its geographical north pole.
www.indiangyan.com /books/magnetbooks/magnetic_cure/what_is_magnet.shtml   (1836 words)

  
  Magnet - Wikipedia, the free encyclopedia
All magnets are dipoles: that is, all magnets have a north and a south pole.
The end of a magnet that points toward the Earth's geographic North Pole is labeled as the north pole of the magnet; correspondingly, the end that points south is the south pole of the magnet.
Calculating the attractive or repulsive force between two magnets is, in the general case, an extremely complex operation, as it depends on the shape, magnetization, orientation and separation of the magnets.
en.wikipedia.org /wiki/Magnet   (2375 words)

  
 Learn more about Magnetism in the online encyclopedia.   (Site not responding. Last check: 2007-11-05)
Magnetic forces are fundamental forces that arise due to the movement of electrically charged particles.
The overall magnetic moment of the atom is thus the sum of all of the magnetic moments of the individual electrons, accounting for moment cancellation between properly paired electrons.
Magnetic material may be modelled by a system of spins located at positions in a lattice, where the interaction of neighboring spins contributes to the total energy of the system and the states of the spins change according to some non-deterministic (probabalistic) rule (the dynamics of the system).
www.onlineencyclopedia.org /m/ma/magnetism.html   (641 words)

  
 Magnet - Open Encyclopedia   (Site not responding. Last check: 2007-11-05)
Magnet is also the name of a commune in the Allier département, in France, and Magnet, Nebraska is a town in the United States.
Such materials consist of atoms or molecules that have each a magnetic field (resulting from the spin angular momentum of electrons within them), but objects composed of these materials have magnetic fields only to the extent that these microscopic magnetic fields are positioned to reinforce rather than cancel each other.
Calculating the attractive or repulsive force between two magnets is, in the general case, an extremely complex operation, as it depends on the shape, magnetisation, orientation and separation of the magnets.
open-encyclopedia.com /Magnet   (931 words)

  
 Encyclopedia: Magnet   (Site not responding. Last check: 2007-11-05)
Paramagnetism is the tendency of the atomic magnetic dipoles, due to quantum-mechanical spin, in a material that is otherwise non-magnetic to align with an external magnetic field.
Magnetic tape is a non-volatile storage medium consisting of a magnetisable coating on a thin plastic strip.
Neodymium magnet on a bracket from a hard drive A neodymium magnet (also, but less specifically, called a rare-earth magnet) is a powerful magnet made of a combination of neodymium, iron, and boron — Nd2Fe14B.
www.nationmaster.com /encyclopedia/Magnet   (4432 words)

  
 Superconducting magnet attracts molecular research
Weighing in at roughly seven and a half tons, the magnetic resonance (MR) spectrometer was funded by a $2 million grant from the National Institutes of Health (NIH) in a stiff competition among research universities.
Magnetic resonance is a physical phenomenon based on the magnetic property of an atom's nucleus.
Magnetic resonance spectroscopy was first described more than a half century ago, and is related to MRI (magnetic resonance imaging) used in hospitals as a soft-tissue diagnostic tool.
www.eurekalert.org /pub_releases/2005-11/bu-sma110205.php   (521 words)

  
 Molecular Orbital Theory
Molecular orbital theory is more powerful than valence-bond theory because the orbitals reflect the geometry of the molecule to which they are applied.
Molecular orbitals are obtained by combining the atomic orbitals on the atoms in the molecule.
To sort out the relative energies of the six molecular orbitals formed when the 2p atomic orbitals on a pair of atoms are combined, we need to understand the relationship between the strength of the interaction between a pair of orbitals and the relative energies of the molecular orbitals they form.
chemed.chem.purdue.edu /genchem/topicreview/bp/ch8/mo.html   (1304 words)

  
 Quantum tunnelling in molecular magnets
In the last decade, molecular chemistry has had a large impact in the field of nanoscale magnetism by providing molecular magnets -large molecules or clusters with magnetic properties.
Molecular magnetic clusters have small spins compared to usual fine magnetic particles and quantum effects are more likely to be revealed in these systems.
Molecular magnets exhibit novel properties, such as molecular magnetic bistability, macroscopic quantum tunnelling of magnetisation, quantum phase interference, quantum coherence, and giant magnetostriction.
www.oxinst.com /SCNRMP38.htm   (389 words)

  
 Magnet Article, Magnet Information   (Site not responding. Last check: 2007-11-05)
Such materials consist of atoms or molecules that have each have a magnetic field (resulting from the spin angular momentum of electrons within them), but objects composed of these materials have magnetic fields only to the extent that thesemicroscopic magnetic fields are positioned to reinforce rather than cancel each other.
The mistaken idea of a magnetic pole as a thing rather than as a description of the orientation of a magnetic field invitesthe expectation that cutting a magnet in half should separate the two poles.
There are theories involving the possibility ofnorth and south magnetic monopoles, which could be mounted at theends of, say, a wooden rod to produce a dipole magnet.
www.anoca.org /magnetic/field/magnet.html   (782 words)

  
 People directly involved in the Network at Grenoble:   (Site not responding. Last check: 2007-11-05)
The application of a magnetic field of a few Tesla below 1 K allows to observe tunneling (i) between the states m=-10 and m=10-n with n=8 to 11 if the field is longitudinal, or (ii) between the two ground-states m~-10 and m~10 if the field is transverse.
Nanometer-sized magnetic particles have generated continuous interest as the study of their properties has proved to be scientifically and technologically very challenging.
The discussion is focused on the Fe8 molecular magnet with S = 10because it is the first system where studies in the pure quantum regime were possible.
www.chim1.unifi.it /mnmag/grenoble/MidTerm.htm   (3161 words)

  
 LMI : Research topics, molecular magnet
His project is the design and study of molecular based materials with switchable or optically activated magnetic properties or for which the magnetic properties will be strongly correlated with optical properties The major target is their incorporation in devices for information storage.
The difference lies in the molecular nature of the spin carriers which may be inorganic (metal complexes) or organic (free radicals) which allows non classical functions by combining magnetic properties with others.
One of the main interest in single molecular magnets come from the so call Macroscopic Quantum Tunnelling effect of the magnetic moment due to the fact they have properties in between the quantum behaviour of isolated spin and those of a solid.
www.univ-lyon1.fr /lmi/A/LMI-molecular-magnet.htm   (507 words)

  
 Research Group of Jorge H. Rodriguez
The theoretical investigation of "molecular magnets" is of interest not only due to their novel properties, which are borderline between quantum and classical phenomena, but also due to their potential technological applications which range from quantum computing to memory storage devices.
Prominent examples are the ferrimagnetic nanostructures known as Fe8 and Mn12 which exhibit quantun tunneling of their sublattice magnetizations (macroscopic quantum tunneling) and magnetic hysteresis not given by long-range-order interactions but having a purely molecular origin.
Athough much experimental and theoretical effort has been devoted to understanding spin dynamics and tunneling rates in molecular magnets, little attention has been given to the first principle calculation of their electronic structures and to the computational prediction of their magnetic properties such as magnetic anisotropies.
www.physics.purdue.edu /biomolecular_physics/molecular_spintronics.shtml   (702 words)

  
 50-year-old magnetic mystery solved; quantum structure obeys classical physics
In contrast, the molecular magnet Cr8 is so small that quantum mechanics -- the science that describes the interactions of subatomic particles -- should rule its behavior.
Materials such as Cr8 are called molecular magnets, because they are composed of only a small number of atoms that form a large molecule.
But Anderson's theory suggests that the magnet will generate a second kind of excitation called the Néel excitation when the electrons in its atoms are at their lowest possible energy state.
www.eurekalert.org /pub_releases/2004-01/osu-5mm010604.php   (1107 words)

  
 Wikinfo | Magnet
The end of a freely suspended magnet that starts to point more or less towards the Earth's geographical North Pole, is called the magnetic south pole; correspondingly, the other end that ends up pointing south is the magnetic north pole.
Unless magnetic monopoles turn out to exist, we will never see a north pole without a south one, because in all the magnets that have been found of or made those are complementary directions rather than two separable things.
Magnet is also the name of a commune in the Allier département, in France
www.wikinfo.org /wiki.php?title=Magnet   (806 words)

  
 Irinel Chiorescu :: research   (Site not responding. Last check: 2007-11-05)
The molecular magnets are formed of exchanged decoupled large magnetic molecules arranged within a crystal.
In the high spin Mn molecular magnets my work was oriented towards experiments on the quantum tunneling and numerical calculations (matrix diagonalization).
molecular magnet the work was focused on the coupling between the total molecular spin 1/2 and phonons.
vortex.tn.tudelft.nl /~chiorescu/research.html   (744 words)

  
 MAGNet - Multiscale Analysis of Genomic and Cellular Networks
This activity is coordinated by a complex network of biochemical interactions largely determined by molecular structures and physiochemical properties which control common intra and inter-cellular functions over a wide range of scales.
Additionally, the emerging complexity of these molecular interactions in the cell calls for a new level of sophistication in the design of genome-wide computational approaches.
However, the field is still fragmented and a homogeneous framework for the comprehensive mapping and analysis of molecular cellular interactions, while still elusive, constitutes a highly relevant scientific goal.
magnet.c2b2.columbia.edu   (280 words)

  
 NMR   (Site not responding. Last check: 2007-11-05)
The interaction between these tiny molecular magnets (present in molecules) and a very strong laboratory magnet is the basis of NMR phenomenon.
In the absence of a laboratory magnetic field, the nuclear spins in a molecular sample are oriented at random and thus producing no net magnetic moment to the sample.
Greater the shielding of a particular hydrogen by local magnetic fields, the greater the strength of the applied field is necessary to bring that hydrogen into resonance.
www.wiu.edu /users/mftkv/CHEM500/LECT1.html   (1982 words)

  
 Spin 1/2 molecular magnet V15
Magnetization measurements have been performed and despite the absence of a barrier, magnetic hysteresis is observed over a timescale of several seconds.
This new phenomenon characterized by a ``butterfly'' hysteresis loop is due to the effect of the environment on the quantum rotation of the entangled 15 spins of the molecule, in which the phonon density of states is not at its equilibrium (phonon bottleneck).
At a given temperature, the equilibrium magnetization curve can be approximated by the median of the two branches of a low sweeping rate hysteresis loop.
lab-neel.grenoble.cnrs.fr /themes/nano/v15   (1098 words)

  
 Media Center - NHMFL Press Releases - February 14, 2007 - FSU Professor's Research Could Lead to Vastly Improved ...
Working at FSU and the magnet lab, Dalal and another FSU researcher, chemistry graduate teaching assistant Vasanth Ramachandran, were able to synthesize a substance known as Fe that is one of the strongest magnets known.
Molecular magnets such as Fe hold great potential for other applications as well, he said.
Using current technologies, the magnetic coating on a disc's surface is about 1 micron – one-millionth of a meter – in depth.
www.magnet.fsu.edu /mediacenter/news/pressreleases/2007february14.html   (588 words)

  
 Sub Pages   (Site not responding. Last check: 2007-11-05)
Molecular magnets exhibit many novel nanostructure magnetic properties and potential application, while most of the present studies concentrate on the collective spin dynamics and quantum magnetic tunneling of molecular spin based on a phenomenal Heisenberg spin model, the spin is the only relevant freedom degree.
Starting from the orbital-degenerate Hubbard model, we obtain the superexchange magnetic coupling matrix for different orbitals between Mn ions by the second-order perturbation approach, orbital-dependent couplings among Mn ions stablize the S=10 configuration as realistic ground state and the groundstate energy gap by the exact diagonalization.
Therefore the anisotropic spin interaction in Mn_{12}Ac is attributed to the spatial-symmetry-broken orbital interaction, the orbital dynamics is thus involved in the spin dynamics.
www.math.utah.edu /etopim/text/minabstracts/zou.html   (164 words)

  
 [No title]   (Site not responding. Last check: 2007-11-05)
The scientific activity of the Basel group has mainly been focussed on exploring the possibility of using magnetic molecular clusters for quantum computing techniques and developing new theoretical models for quantum coherence phenomena in macroscopic objects.
Hence, molecular magnets such as Fe_8 and Mn_12 are promising candidates for the FIRST REALIZATION OF A QUANTUM COMPUTING ALGORITHM with a solid state device.
Although these molecular magnets are probably the most promising candidates for the observation of coherent quantum phenomena currently available, they have received considerably
www.chim1.unifi.it /mnmag/bern/MidTerm.htm   (502 words)

  
 The Hindu News Update Service
Their paper, "Efficacy of the Single-Molecule Magnet Fe8 for Magnetic Resonance Imaging Contrast Agent Over a Broad Range of Concentration," was published in the current issue of Polyhedron, a rigorously peer-reviewed science journal, according to a news bulletin from the University in Tallahasse, Florida.
It has a powerful magnetic field, which is obviously important in generating a very clear image with an MRI device.
Molecular magnets such as Fe8 hold great potential for other applications as well, he said.
www.hindu.com /thehindu/holnus/008200702150310.htm   (503 words)

  
 Molecules on Rye? - Science - RedOrbit
The new type of molecular magnet, known as a sandwich cluster, is being studied in a joint research project of the U.S. Department of Energy's Argonne National Laboratory, the University of Chicago, and Keio University in Japan.
The molecular magnets may one day lend a hand in ultrasmall, fast, and energy-efficient computer storage systems.
Molecular magnets could be useful for energy-efficient computer storage systems.
www.redorbit.com /news/display?id=134498&source=r_science   (357 words)

  
 Technology Review: TR35
His first target is the molecular magnet, a chemical structure whose electrons can be set spinning in synchrony by a magnetic field.
Molecular magnets are a potential replacement for the increasingly crowded metallic films that constitute computer hard drives.
Each molecular magnet could represent one bit of memory, enabling storage densities a thousand times greater than those of the best existing films.
www.technologyreview.com /TR35/Profile.aspx?Cand=T&TRID=279   (229 words)

  
 C&EN: SCIENCE & TECHNOLOGY - SINGLE-MOLECULE MAGNETS EVOLVE
Conventional magnets rely on the collective behavior of the unpaired electron spins of hundreds of thousands or millions of individual metal centers in a particle or bulk material.
In these compounds, some of which are magnets at room temperature, the magnetism arises from the collective unpaired electrons of the bulk material, similar to iron or cobalt metal particles.
Magnetic anisotropy is the nonuniform distribution of magnetic properties in a molecule or particle.
pubs.acs.org /cen/science/8250/8250sci1.html   (3077 words)

  
 Sandwich clusters may improve magnetic memory storage
ARGONNE, Ill. (Nov. 11, 2004) — A new type of molecular magnet known as a “sandwich cluster” is being studied under a joint research collaboration between the U.S. Department of Energy's Argonne National Laboratory, the University of Chicago and Keio University in Japan.
These molecular magnets could be useful for magnetic storage or spintronics, developing technologies that could enable computers to have ultra-small storage capabilities with faster and more energy-efficient systems.
The combined effort among the three institutions allows advanced research on the development of the new molecular magnets, which may be valuable candidates for magnetic storage and spintronics.
www.anl.gov /Media_Center/News/2004/news041111.html   (583 words)

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