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Author (up) Sereni, J.G.; Gomez Berisso, M.; Braghta, A.; Schmerber, G.; Kappler, J.P. doi  openurl
  Title Unstable Shastry-Sutherland phase in Ce2Pd2Sn Type Journal Article
  Year 2008 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B  
  Volume 80 Issue 2 Pages 022428  
  Keywords cerium alloys; crystal field interactions; entropy; ferromagnetic materials; frustration; magnetic anisotropy; magnetic hysteresis: magnetic transitions; palladium alloys; tin alloys  
  Abstract Thermal (CP) , magnetic ( M and χac ), and transport (ρ) measurements on Ce2Pd2Sn are reported. High-temperature properties are well described by the presence of two excited crystal-field levels at (65±5)K and (230±20)K , with negligible hybridization (Kondo) effects. According to literature, two transitions were observed at TM=4.8K and TC=2.1K , respectively. The upper transition cannot be considered as a standard antiferromagnetic because of frustration effects in a triangular network of Ce atoms and the positive sign of the paramagnetic temperature θPLT=4.4K . The nature of the intermediated phase is described accounting for the formation of ferromagnetic (F) Ce dimers disposed in a quasi-two-dimensional square lattice, resembling a Shastry-Sutherland pattern. According to hysteretic features in ρ(T) and χac(T) , the lower F transition is of first order, with CP(T<TC) revealing a gap of anisotropy Eg≈7K .  
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  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 563  
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Author (up) Sereni, J.G.; Gómez Berisso, M.; Schmerber, G.; Kappler, J.P. url  doi
openurl 
  Title Suppression of the Shastry-Sutherland phase in Ce2 Pd 2 Sn at a field-induced critical point Type Journal Article
  Year 2010 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B Condens. Matter Mater. Phys.  
  Volume 81 Issue 18 Pages 184429  
  Keywords  
  Abstract The magnetic phase diagram of Ce2 Pd2 Sn is investigated through the field dependence of thermal, transport, and magnetic properties at low temperature. The upper transition, TM =4.8 K is slightly affected by magnetic field up to B=1 T whereas the lower one T C (B) rapidly increases from 2.1 K joining TM in a critical point at Tcr = (4.1±0.2) K for Bcr = (0.11±0.01) T. At that point, the intermediate phase, previously described as an unstable Shastry-Sutherland lattice, is suppressed. A detailed analysis around the critical point reveals a structure in the maximum of the ∂ M/∂ B (B) derivative, which may be related to a step in magnetization predicted by theory for the mentioned lattice. © 2010 The American Physical Society.  
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  ISSN 10980121 (ISSN) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ berisso @ Serial 595  
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Author (up) Sereni, J.G.; Schmerber, G.; Berisso, M.G.; Chevalier, B.; Kappler, J.P. url  doi
openurl 
  Title Tricritical point and suppression of the Shastry-Sutherland phase in Ce2(Pd1−xNix)2Sn Type Journal Article
  Year 2012 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B  
  Volume 85 Issue 13 Pages 134404  
  Keywords  
  Abstract Structural, magnetization, and heat capacity measurements were performed on Ce2(Pd1−xNix)2Sn compounds covering the full range of the Mo2FeB2 structure stability (0⩽x⩽0.25). In this system, the two transitions observed in Ce2Pd2Sn (antiferromagnetic TN=4.8 K and ferromagnetic TC=2.1 K) converge into a tricritical point at Tcr≈3.4 K for xcr≈0.3, where the intermediate antiferromagnetic (AF) phase is suppressed. The decrease of the TN(x) phase boundary is due to an incipient Kondo screening of the Ce-4f moments. This effect and the increase of local atomic disorder affect the formation of Ce-magnetic dimers on which the Shastry-Sutherland lattice (SSL) builds up. On the contrary, the TC(x) transition to the ferromagnetic ground state increases as a consequence of the weakening of the intermediate phase. Applied magnetic fields also suppress the AF-SSL phase as it was already observed in the stoichiometric compound.  
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  Publisher American Physical Society Place of Publication Editor  
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  Notes Approved no  
  Call Number BT @ berisso @ 10.1103/PhysRevB.85.134404 Serial 639  
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Author (up) Sereni, J.G.; Schmerber, G.; Kappler, J.P. doi  openurl
  Title Thermodynamic Behavior of Ce Compounds Close to a T->0 Critical Point Type Journal Article
  Year 2013 Publication IEEE Transactions on Magnetics Abbreviated Journal IEEE Trans. Magn.  
  Volume 49 Issue 8 Pages 4647-4651  
  Keywords cerium compounds; critical points; entropy; palladium compounds; specific heat; CePd3Bx; CePd3Bex; cerium compounds; critical point; entropy; specific heat; thermodynamic behavior; Compounds; Entropy; Heating; Saturation magnetization; Temperature dependence; Temperature measurement; Thermodynamics; Cerium; magnetic properties; thermodynamics  
  Abstract There is a reduced group of Ce very heavy Fermions (VHF) which do not order magnetically down to at least T ≈ 500 mK because they are very close to a Tord = 0 critical point. These compounds are at the top of the limT→ 0 Cm/T specific heat values because they collect very high density of low energy excitations. From the analysis of Cm(T)/T and entropy Sm(T) dependencies performed on selected CePd3Mx ternaries (where M = B and Be) a quantitative evaluation of an upper limit for the density of excitations can be proposed. These observations exclude any evidence of Cm(T)/T divergency as T→ 0 in agreement with thermodynamic laws. A comparison with selected Yb-base VHF supports these features.  
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  ISSN 0018-9464 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 664  
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Author (up) Sereni, J.G.; Trovarelli, O.; Schaf, J.; Schmerber, G.; Kappler, J.P. doi  openurl
  Title Extremely Low Density of States in CePd7 Type Journal Article
  Year 1991 Publication Modern Physics Letters B Abbreviated Journal Mod. Phys. Lett. B  
  Volume 5 Issue 18 Pages 1249-1253  
  Keywords  
  Abstract The low temperature specific heat and magnetic susceptibility measurements, up to room temperature, on CePd7 are reported. The Sommefeld coefficient gamma and the Pauli susceptibility chio were found to have the lowest values within the Ce compounds: gamma = 9.8 mJ/mole K2 and chio = 0.14 × 10-3 emu/mole. The ratio chio/gamma = 0.014 emu K2/J is that of a free electron, instead of an intermediate valence system (0.036 emu K2/J). Such a value suggests complete delocalization of the Ce 4f electrons.  
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  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 684  
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Author (up) Sereni, J.G.; Trovarelli, O.; Schmerber, G.; Kappler, J.P. doi  openurl
  Title Non-Fermi-liquid signatures in stoichiometric Ce7Ru3 at ambient pressure Type Journal Article
  Year 1999 Publication Physica B – Condensed Matter Abbreviated Journal Physica B  
  Volume 259-261 Issue Pages 405-406  
  Keywords  
  Abstract Magnetic (chi(-1) proportional to root T) and thermal (C-p/T proportional to – log T) temperature dependencies of stoichiometric Ce7Ru3 are studied in order to establish whether its low temperature behavior corresponds to that of a non-Fermi-liquid system at normal pressure. Despite its reduced unit cell volume this compound shows a broadened antiferromagnetic transition, which involves only a small fraction of the expected entropy at T = T-n = 0.8 K. Scaling properties of C-p/t = -A log(t) + ETo (with t = T/T-o) under magnetic field (B) are fulfilled with A = 7.2 J and E = 0.07 B. The thermal characteristics of the transition itself are compared with those of other Ce compounds that also exhibit a “Lambda-shape” in the C-p/T(T) dependence around T-n. (C) 1999 Elsevier Science B.V. All rights reserved.  
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  Series Volume Series Issue Edition  
  ISSN 0921-4526 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000079315700179 Approved no  
  Call Number BT @ hernan @ Serial 82  
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Author (up) Sereni, J.G.; Trovarelli, O.; Schmerber, G.; Kappler, J.P. doi  openurl
  Title Comparative study of thermal and magnetic properties of CeTyX4-y ferromagnets Type Journal Article
  Year 1997 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B  
  Volume 56 Issue 9 Pages 5380-5386  
  Keywords  
  Abstract Low-temperature thermal (specific heat, C-P) and magnetic [ac susceptibility, chi(ac), and isothermal magnetization M(B)] measurements on CeTyX4-y ferromagnets (with T = Ni, Cu, Pd, Ag, Au, and X = Ga, Al, with 0.3 < y < 0.7) are reported. With the exception of T = Ni, all compounds with X = Ga show a typical second-order ferromagnetic transition. In the case of T = Ni, magnetic correlations set in at T approximate to 3T(C), (T-C being the Curie temperature) and the C-P(T) and chi(ac)(T) maxima (at 3.3 and 4.2 K, respectively) do not coincide, while the M(B) curves reveal an antiferromagnetic character at lower temperatures. In these systems, the magnetic entropy of the ordered phase is larger than 85% of Rln2, in coincidence with the low values of the Sommerfeld coefficient gamma less than or equal to 10 mJ/mol K-2. For T = Ag and X = Al, a strong diamagnetic signal was observed at T-s = 0.63 K in chi(ac)(T), with the characteristics of a superconducting component. The thermodynamical properties of these compounds confirm the lack of hybridization when the Ce atom is in a ferromagnetic ground state.  
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  Series Volume Series Issue Edition  
  ISSN 0163-1829 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1997XW94200062 Approved no  
  Call Number BT @ hernan @ Serial 89  
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Author (up) Sereni, J.G.; Trovarelli, O.; Schmerber, G.; Kappler, J.P. doi  openurl
  Title Coexistence of magnetic order and heavy fermion behavior in Ce7X3 Type Journal Article
  Year 1992 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.  
  Volume 108 Issue 1-3 Pages 183-184  
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  Abstract Low temperature specific heat and magnetic susceptibility measurements on Ce7X3 (X = Rh, Ni) compounds are reported. Ce7Rh3 shows an onset of spontaneous magnetization at 7.2 K. About 40% of the expected R ln 2 entropy gain is found in the paramagnetic phase, related to a gamma(HT) = 1.1 J/K2 mol specific heat coefficient. In Ce7Ni3 an antiferromagnetic transition is observed at 1.7 K, superimposed to a large C(p)/T electronic contribution, described by a gamma(HT) = 0.9 J/K2 mol coefficient for T > 10 K. These results are interpreted in terms of the three different crystal sublattices of Ce. The entropy gain related to each transition allows to identify the behaviour of each sublattice. In the case of Ce7Ni3 one sublattice behaves as a heavy fermion system, with a value of C(p)/T = 3.3 J/K2 Ce at. Such a behaviour is confirmed under an applied magnetic field.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0304-8853 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1992HH32900075 Approved no  
  Call Number BT @ hernan @ Serial 113  
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Author (up) TROVARELLI, O.; SERENI, J.G.; SCHMERBER, G.; KAPPLER, J.P. openurl 
  Title COEXISTENCE OF KONDO AND SPIN-GLASS BEHAVIOR IN CE4Y3NI3 Type Journal Article
  Year 1995 Publication JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Abbreviated Journal  
  Volume 140 Issue Pages 1211-1212  
  Keywords  
  Abstract Magnetic susceptibility chi and specific heat C-p measurements on Ce4Y3Ni3 are presented. The temperature of the maximum of chi(ac)(T) and C-p(T) shifts with frequency and applied field respectively, as expected for a spin glass (SG) system. The C-p (T --> 0) dependence corresponds to that of an anisotropic SG. According to the entropy gain two Ce atoms are involved in the SG contribution and two exhibit Kondo effect.  
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  ISSN 0304-8853 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1995QM07400233 Approved no  
  Call Number BT @ hernan @ Serial 101  
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Author (up) TROVARELLI, O.; SERENI, J.G.; SCHMERBER, G.; KAPPLER, J.P. doi  openurl
  Title Low-temperature magnetic and thermal properties of CePdSb Type Journal Article
  Year 1994 Publication Physical Review B – Condensed Matter and Materials Physics Abbreviated Journal Phys. Rev. B  
  Volume 49 Issue 21 Pages 15179-15183  
  Keywords  
  Abstract Low-temperature ac and dc magnetic susceptibility, high-field magnetization, and specific-heat measurements have been carried out on CePdSb. The magnetic measurements confirm the ferromagnetic transition at T(C) = 17 K as previously reported. However, no anomaly in the specific heat is observed at that temperature, but only the onset of the magnetic contribution, C(M)(T). The maximum of C(M)(T) is observed at T(max) = 9.7 K. The lack of a C(M)(T) jump at T(C) is discussed in terms of the comparison of the exchange integrals between first- and second-nearest magnetic neighbors. Depending on their relative values, the magnetic structure can behave as low dimensional or incommensurate. The entropy of the magnetic phase (Rln2) and the low density of states (gamma = 11 mJ/mol K2) excludes a Kondo-lattice character for this compound.  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0163-1829 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:A1994NR42500043 Approved no  
  Call Number BT @ hernan @ Serial 106  
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