| Records |
Author  |
Braun, E.; Bürger, A.; Nieva, G.L.; Roden, B.; Sereni, J.G. |
| Title |
Unexpected magnetic behaviour in a singlet crystal field ground state induced by Tb 4f-instability |
Type |
Journal Article |
| Year |
1988 |
Publication |
Zeitschrift für Physik B Condensed Matter |
Abbreviated Journal |
Z. Phys. B |
| Volume |
70 |
Issue |
2 |
Pages |
187-192 |
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| Abstract |
The magnetic susceptibility (chi) of Th1-x Tb x alloys (with 5<x<55a/o Tb) in the range of 1 K<T<350K and the specific heat (forx=1.5a/o Tb) for 0.5<T<10 K were measured. A maximum in chi(T) was observed at a temperature which depends on concentration. The crystal field level scheme that fits the specific heat measurements shows two non-magnetic singlets as lowest levels. Such ambiguity is discussed within the framework of the 4f-Tb instability. The results are in agreement with the matrix superconductiveT c decrease. The contribution of the interconfigurational mixing on chi and the specific heat is also discussed. |
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| ISSN |
0722-3277 |
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| Notes |
ISI:A1988M112900009 |
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| Call Number |
BT @ hernan @ |
Serial |
127 |
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| Author |
Braun, E.; Bürger, A.; Roden, B.; Sereni, J.G. |
| Title |
Spin glass-like behaviour of the singlet ground state system: ThTb |
Type |
Journal Article |
| Year |
1988 |
Publication |
Solid State Communications |
Abbreviated Journal |
Solid State Commun. |
| Volume |
66 |
Issue |
11 |
Pages |
1141-1144 |
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| Abstract |
We have studied the temperature and field dependence of the magnetic susceptibility, X, on the single-ground-state Th1?nTbn system, in the 0.2 < n < 0.6 concentration range. The characteristic maximum of a spin glass transition was found at a temperature Tg, which increases linearly with the impurity concentration. As expected, the maximum of X is reduced by the increment of the applied magnetic field. The spin glass order parameter, as well as its critical exponent were evaluated by using the Sherrington-Kirkpatrick theory. |
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| ISSN |
0038-1098 |
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no |
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BT @ pedrazp @ |
Serial |
577 |
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| Author |
Braun, E.; Jackel, G.; Roden, B.; Sereni, J.G.; Wohlleben, D. |
| Title |
Comparative study of the specific heat of superconducting and non-superconducting YBa2Cu3O7-x |
Type |
Journal Article |
| Year |
1988 |
Publication |
Zeitschrift für Physik B Condensed Matter |
Abbreviated Journal |
Z. Phys. B |
| Volume |
72 |
Issue |
2 |
Pages |
169-173 |
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| Abstract |
We have measured the specific heat, the electrical resistance and the magnetic susceptibility of YBa2Cu3O7−x in a superconducting (sc) and in a non-superconducting (nsc) version. The latter was obtained by inducing a small loss of oxygen. In the sc sample we find a jump of the specific heat with ΔC=3.6 J mole−1 K−1. Below the maximum nearT c the specific heat of the sc version drops too fast for an electronic effect alone: there is a cross-over from excess to deficiency already at 0.9T c . The specific heat of the nsc version shows a change of slope in the temperature range between 70 and 80 K, which indicates the existence of a second specific heat anomaly, which apparently exists independently of that due to the onset of superconductivity and explains at least partially the premature crossover. |
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0722-3277 |
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| Notes |
ISI:A1988P796500004 |
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no |
| Call Number |
BT @ hernan @ |
Serial |
125 |
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| Author |
Sereni, J.G.; Nieva, G.; Huber, J.G.; Braun, E.; Oster, F.; Bruck, E.; Roden, B.; Wohlleben, D. |
| Title |
Evidence for 4f-instability of dilute terbium in thorium |
Type |
Journal Article |
| Year |
1987 |
Publication |
Journal of Magnetism and Magnetic Materials |
Abbreviated Journal |
J. Magn. Magn. Mater. |
| Volume |
63-64 |
Issue |
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Pages |
597-599 |
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| Abstract |
We have measured the specific heat of dilute Th1?xTbx alloys (0.44 < x < 2.15 a/o), which rises linearly between 0.4 and 0.9 K with a slope of ?C/T ? 450 mJ/K2molTb followed by a Schottky anomaly with a maximum near 3.8 K. The high temperature ??T product was found to be 4% lower than that of Tb3+. The resistivity shows no minimum at low temperatures. Discussion is made in terms of non-integral valence of Tb. |
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| ISSN |
0304-8853 |
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| Notes |
ISI:A1987G356900173 |
Approved |
no |
| Call Number |
BT @ hernan @ |
Serial |
129 |
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