Magnetic properties of copper acetate at low temperatures
TL;DR: In this paper, the abnormal magnetic behavior of the single crystal of Cu(CH3COO)2H2O is discussed in the light of its magnetic and fine structure studies, and the large magnetic anisotropy and the sharp fall of its principal susceptibilities with the fall of temperature may be attributed to anisotropic negative exchange interaction between paramagnetic ions.
Abstract: The abnormal magnetic behaviour of the single crystal of Cu(CH3COO)2H2O is discussed in the light of its magnetic and fine structure studies. The large magnetic anisotropy and the sharp fall of its principal susceptibilities with the fall of temperature may be attributed to anisotropic negative exchange interaction between paramagnetic ions.
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TL;DR: The magnetic anisotropy of binuclear copper(II) acetate monohydrate has been determined by a null deflexion method at temperatures between 80 and 300 K.
Abstract: The magnetic anisotropy of binuclear copper(II) acetate monohydrate has been redetermined by a null deflexion method at temperatures between 80 and 300 K. The new data establish that all previously reported anisotropy measurements have been seriously in error, presumably due to difficulties in correctly identifying the principal crystal axes. The previous necessity to invoke temperature-dependent values for the exchange integral J$\_{\text{eff}}$ and the g-factors now disappears and the new experimental anisotropies conform closely to Bleaney & Bowers (1952 b) theory with constant values for the disposable parameters. The magnetic anisotropy is especially sensitive to anisotropy in the high-frequency term of the susceptibility expressions. This enables the controversial electronic spectrum to be assigned in terms of the ligand field transitions 11 000 cm$^{-1}$ (d$\_{z^{2}}$ $\leftarrow $ d$\_{x^{2}-y^{2}}$); 14 400 cm $^{-1}$ (d$\_{xz,yz}$ $\leftarrow $ d$\_{x^{2}-y^{2}}$); 17 000 cm $^{-1}$ (d$\_{xy}$ $\leftarrow $ d$_{x^{2}-y^{2}}$). The nature of the chemical bonding and exchange interaction is discussed.
45 citations
10 citations
28 Feb 2018
TL;DR: In this article, a rare example of an ABBABB coupled linear chain comprised of alternating dicopper(II) tetraacetate units bridged to copper (II) acetate monomer units via axial η2:η1:µ2 coordinated acetate is reported.
Abstract: One-dimensional metal–organic coordination polymers make up a class of compounds with potential towards the development of practical, new magnetic materials. Herein, a rare example of an ABBABB coupled linear chain comprised of alternating dicopper(II) tetraacetate units bridged to copper(II) acetate monomer units via axial η2:η1:µ2 coordinated acetate is reported. Examination of the structure, determined by small molecule X-ray crystallography, shows that each Cu(II) ion is in a dx2–y2 magnetic ground state. Magnetic susceptibility and magnetization data were collected and, consistent with the structural interpretation, demonstrate that the Cu(II) dimer (paddlewheel) exhibits classic antiferromagnetic exchange, while the S = 1/2 Cu(II) monomer is uncompensated in the ground state (low temperature regime.) Data were therefore fitted to a modified Bleaney-Bowers model, and results were consistent with the only other reported chain in this class for which magnetic data are available.
6 citations
TL;DR: In this paper, the magnetic behavior of a cupric acetate monohydrate single crystal is discussed in the light of crystal structure and Bleaney and Bowers theory and it is suggested that Guha's magnetic data are erroneous, and that his suggestion of anisotropic exchange interaction is unnecessary.
Abstract: The magnetic behaviour of a cupric acetate monohydrate single crystal is discussed. Results reported by various workers are discussed in the light of crystal structure and Bleaney and Bowers theory. It is suggested that Guha's magnetic data are erroneous, and that his suggestion of anisotropic exchange interaction is unnecessary. Bleaney and Bowers theory is shown to give good agreement with experimental results with a constant value of exchange integral and without including anisotropic exchange term in the Hamiltonian.
2 citations
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TL;DR: In this article, the paramagnetic resonance spectrum of copper acetate is anomalous in that it resembles that of an ion of spin 1, and its intensity decreases as the temperature is lowered.
Abstract: The paramagnetic resonance spectrum of copper acetate is anomalous in that it resembles that of an ion of spin 1, and its intensity decreases as the temperature is lowered. The latter is correlated with the decreasing susceptibility found by Guha (1951). The following hypotheses are suggested: (1) the crystalline field acting on each copper ion is similar to that in other salts such as the Tutton salts; (2) isolated pairs of copper ions interact strongly through exchange forces, each pair forming a lower singlet state and an upper triplet state, the latter only being paramagnetic. On this basis both the fine structure and the hyperfine structure of the spectrum have a simple explanation, and the theory also predicts a small initial splitting of the triplet state of the same order as that found experimentally. The unit cell of the crystal contains two differently oriented pairs of ions, and, using an empirical value for the exchange parameter, fair agreement with the susceptibility measurements of Guha is obtained.
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TL;DR: In this paper, the principal magnetic susceptibilities and anisotropies of a number of salts of the iron group have been measured from room temperature down to about 80° K. The results are discussed in the light of the crystalline field theory developed by Van Vleck, and Schlapp & Penney.
Abstract: The principal magnetic susceptibilities and anisotropies of a number of salts of the iron group have been measured from room temperature down to about 80° K. The results are discussed in the light of the crystalline field theory developed by Van Vleck, and Schlapp & Penney. 1. Both the Mn ++ and Fe +++ ions being in the S -state, the anisotropies are extremely feeble, and the temperature variation of the susceptibility follows almost exactly the Curie law. 2. In the Stark pattern for Cr +++ the lowest level is a singlet, with a (2 s + l)-fold spin degeneracy, which is far removed from the upper levels, and so the ion behaves as if it were in the S -state. 3. The spin-orbit coupling of Ni ++ is much greater than that of Cr +++ . This is responsible for an appreciable anisotropy and deviation from the Curie law. These deviations are utilized to calculate the crystal field constants. It is found that both the cubic and rhombic parts of the field are nearly of the same magnitude in all the nickel salts, and they are practically independent of temperature. 4. The ground level of Co ++ and Fe ++ is a triplet, and hence their magnetic properties are much more sensitive to the rhombic part of the field than in nickel salts. An estimate of the field is made. 5. The copper salts fall into three distinct classes as judged by their magnetic properties. In the first group, to which the Tutton salts belong, the principal moments are different for different directions, but all of them are practically independent of temperature. In the second class the moments are nearly of the same order as before, but they decrease with the lowering of temperature. The double chloride of copper and ammonium is a typical example of this class. To the third class belongs cupric acetate monohydrate, in which the moments are all very low even at room temperature, and they decrease rapidly as the temperature is lowered, the three classes correspond to the non-cubic part of the field being very different, lowest in the first class and highest in the third. 6. In the nickel and ferrous salts there is an axis of magnetic symmetry, though their crystal structures do not lead to it. 7. The magnetic axes of a few crystals change their directions in the temperature range covered. 8. The influence of the covalent binding on the electric field and its effect on the magnetic properties of the ion is discussed.
100 citations
93 citations
TL;DR: Anomalous paramagnetism and exchange interaction in copper acetate have been studied in this article, where the authors propose a method to detect anomalous paramagnetic properties of the metal.
Abstract: (1952). Anomalous paramagnetism and exchange interaction in copper acetate. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 43, No. 338, pp. 372-374.
51 citations