A Model of Single Molecule Magnet Behavior of the [CuIILTbIII(hfac)2]2 Cluster

2008 ◽  
Vol 273-276 ◽  
pp. 227-232
Author(s):  
S. Ostrovsky ◽  
O. Reu ◽  
A. Palii ◽  
Anatoly Yakovlevich Fishman ◽  
Valentin Yakovlevich Mitrofanov ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Experimental Evidence ◽  
Exchange Interaction ◽  
Crystal Field ◽  
Single Molecule ◽  
Magnetization Reversal ◽  
Total Angular Momentum ◽  
Mean Value ◽  
Single Molecule Magnet ◽  
The Mean

We report a model for the explanation of the single molecule magnet behavior of the [CuIILTbIII(hfac)2]2 cluster. The model takes into account the crystal field acting on the TbIII –ion and the exchange interaction between the TbIII and CuII ions. The energies of the low-lying levels are shown to increase with the decrease of the mean value of the z-projection of the total angular momentum of the cluster, thus forming a barrier for magnetization reversal that is in accordance with the experimental evidence.

Exchange-Biasing in a Dinuclear Dysprosium(III) Single-Molecule Magnet with a Large Energy Barrier for Magnetization Reversal

2019 ◽  
Author(s):  
Tian Han ◽  
Marcus J. Giansiracusa ◽  
Zi-Han Li ◽  
You-Song Ding ◽  
Nicholas F. Chilton ◽  
...  
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Energy Barrier ◽  
Magnetic Hysteresis ◽  
Large Energy ◽  
Magnetic Studies ◽  
Bridging Ligands ◽  
Single Molecule Magnet ◽  
Exchange Biasing

A dichlorido-bridged dinuclear dysprosium(III) single-molecule magnet [Dy<sub>2</sub>L<sub>2</sub>(<i>µ</i>-Cl)<sub>2</sub>(THF)<sub>2</sub>] has been made using a diamine-bis(phenolate) ligand, H<sub>2</sub>L. Magnetic studies show an energy barrier for magnetization reversal (<i>U</i><sub>eff</sub>) around 1000 K. Exchange-biasing effect is clearly seen in magnetic hysteresis with steps up to 4 K. <i>Ab</i> initio calculations exclude the possibility of pure dipolar origin of this effect leading to the conclusion that super-exchange <i>via</i> the chloride bridging ligands is important.

scholarly journals A dichlorido-bridged dinuclear Dy(iii) single-molecule magnet with an effective energy barrier larger than 600 K

2019 ◽  
Vol 55 (55) ◽  
pp. 7930-7933 ◽  
Author(s):  
Tian Han ◽  
You-Song Ding ◽  
Zi-Han Li ◽  
Ke-Xin Yu ◽  
Yuan-Qi Zhai ◽  
...  
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Energy Barrier ◽  
Large Energy ◽  
Effective Energy ◽  
Single Molecule Magnet

A large energy barrier for magnetization reversal of about 623 K is observed in a dichlorido-bridged Dy(iii) dimer.

scholarly journals Bakerian Lecture :─On the variation of the specific heat of water, with experiments by a new method

1912 ◽  
Vol 86 (587) ◽  
pp. 254-257 ◽  
Keyword(s):  
Specific Heat ◽  
Experimental Evidence ◽  
Electric Current ◽  
Heat Loss ◽  
Mean Value ◽  
Mechanical Method ◽  
Order Of Accuracy ◽  
Steady Current ◽  
Differential Pair ◽  
The Mean

The question of the variation of the specific heat of water is so fundamental in calorimetry, and the results of different observers and different methods are still so discordant, that no apology is needed for the publication of fresh experimental evidence. The continuous electric method, which I carried out in conjunction with Prof. Barnes, was specially designed to avoid the main sources of error of the older methods in which mercury thermometers and open calorimeters were employed. In this method. the rise of temperature of a steady current of water, heated by a steady electric current in its passage through a fine tube hermetically scaled in a vaccumjacket, was observed with a differential pair of platinum thermometers. Errors due to lag, or to uncertainty of water-equivalent, or to evaporation or heat-loss in transference, were thus eliminated, and a higher order of accuracy was secured in the temperature measurements. The results of the continuous electric method in the case of water showed a variation of specific heat amounting to less than one half of 1 per cent. between 10° and 80°C., with a minimum at 37.6°C., followed by a very slow and steady rise. The mean value from 0° to 100°C. agreed to 1 in 2000 with the experiments of Reynolds and Moorby by the mechanical method, and the values from 5° to 35° C. agreed to a similar order of accuracy with the experiments of Rowland. But the value at 80°C. was 1 per cent. lower than that found by Lüdin's (Zürich, 1895), employing the ordinary method of mixture with an open calorimeter and mercury thermometers. Lüdin's results for the variation over the range 30° to 100°C. agreed more closely with the continuous electric method than those of any previous observers; but showed a minimum at 25°C., and a maximum at 87°C., which could not be reconciled with the experiments of Reynolds and Moorby on the mean specific heat from 0° to 100°C., or with the most probable reduction of Regnault's experiments between 110° and 190°C.

scholarly journals High temperature quantum tunnelling of magnetization and thousand kelvin anisotropy barrier in a Dy2 single-molecule magnet

2021 ◽  
Author(s):  
Haipeng Wu ◽  
Min Li ◽  
Zhengqiang Xia ◽  
Vincent Montigaud ◽  
Olivier Cador ◽  
...  
Keyword(s):  
High Temperature ◽  
Crystal Field ◽  
Single Molecule ◽  
Magnetic Hysteresis ◽  
Single Molecule Magnet ◽  
Quantum Tunnelling ◽  
Field Environment

The control of the crystal field environment within the cis/trans stereoisomers allowed the observation of a significantly enhanced anisotropy barrier to 1300 K and magnetic hysteresis opened up to 16 K.

Mn21Dy Cluster with a Record Magnetization Reversal Barrier for a Mixed 3d/4f Single-Molecule Magnet

2011 ◽  
Vol 50 (2) ◽  
pp. 421-423 ◽  
Author(s):  
Constantina Papatriantafyllopoulou ◽  
Wolfgang Wernsdorfer ◽  
Khalil A. Abboud ◽  
George Christou
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Single Molecule Magnet

scholarly journals An unusual mechanism of building up of a high magnetization blocking barrier in an octahedral alkoxide Dy3+-based single-molecule magnet

2021 ◽  
Author(s):  
Jérôme Long ◽  
Aleksei O. Tolpygin ◽  
Ekaterina Mamontova ◽  
Konstantin A. Lyssenko ◽  
Dan Liu ◽  
...  
Keyword(s):  
Crystal Field ◽  
Single Molecule ◽  
Crystal Field Splitting ◽  
Field Splitting ◽  
Single Molecule Magnet

We report a new octahedral luminescent SMM exhibiting massive crystal-field splitting and an anisotropic barrier of 1385 cm−1.

Single-molecule magnet [Tb(hfac)3(2pyNO)] (2pyNO = t-butyl 2-pyridyl nitroxide) with a relatively high barrier of magnetization reversal

2013 ◽  
Vol 42 (38) ◽  
pp. 13968 ◽  
Author(s):  
Rina Murakami ◽  
Takayuki Ishida ◽  
Shunsuke Yoshii ◽  
Hiroyuki Nojiri
Keyword(s):  
Single Molecule ◽  
Magnetization Reversal ◽  
Single Molecule Magnet

scholarly journals The gyro-magnetic ratio for magnetite and cobalt

1925 ◽  
Vol 108 (748) ◽  
pp. 638-642 ◽  
Keyword(s):  
Angular Momentum ◽  
Permanent Magnets ◽  
Heusler Alloys ◽  
Mean Value ◽  
Steady Current ◽  
Aluminium Wire ◽  
In Series ◽  
Iron Nickel ◽  
Average Variation ◽  
The Mean

In a recent paper a null method of determining the gyro-magnetic ratio was described, and results were given for iron, nickel and the Heusler alloys. The mean value for the three metals was found to be 0·502, with an average variation of 0·004 from the mean. The present communication extends the results to cobalt and magnetite. In this method, which was described fully in the above-mentioned paper, the specimen is suspended vertically along the axis of a solenoid, and magnetised by alternating current of the same frequency as that natural to the suspended system. Apart from disturbing couples, which can be reduced to very small dimensions, the torsional oscillations produced are due only to the angular momentum resulting from the changing magnetism of the specimen. The system is brought to rest by the current, induced by the changing magnetism, in a small “induction” helix coaxial with the specimen. This current passes through a pair of Helmholtz coils in series with an adjustable resistance, and acts on small permanent magnets rigidly fixed to an aluminium wire attached to the lower end of the specimen. When the gyro-magnetic effect is completely neutralised, we have U/M = 4 πncϕ /S i where U = the angular momentum resulting from a change M of magnetic moment, n = the number of turns per centimetre on the “induction” helix, c = torsion constant of suspension, S = neutralising resistance in the circuit of the induction helix necessary to bring the system to rest, i = steady current which when passed through the neutralisation coils produces a deflection ϕ of the permanent magnets.

Breaking Energy of Rubbers

1967 ◽  
Vol 40 (3) ◽  
pp. 815-816
Author(s):  
K. Grosch ◽  
J. A. C. Harwood ◽  
A. R. Payne
Keyword(s):  
Energy Density ◽  
Experimental Evidence ◽  
Test Piece ◽  
Mean Value ◽  
Hysteresis Loss ◽  
Extension Rate ◽  
Extension Curve ◽  
The Mean ◽  
Breaking Energy

Abstract Recent investigations of failure of rubbers and plastics have indicated that hysteresial losses in a polymer are an important factor in fracture. This communication reports experimental evidence that the energy density at break of a polymer is amply related to the hysteresis loss in the polymer. A previously unstrained sample is stressed at a constant extension rate to rupture and the mean value of the rupture load is determined from a number of these measurements. A fresh rubber test piece is then extended under the same conditions until just before rupture, and then retracted at the same rate as was used for extending the rubber. The energy at or near break is determined by measuring the area under the load extension curve, and the hysteresis loss determined from the area between the extension and the retraction curves.

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