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Author Encina, S.; Pedrazzini, P.
Title Low Temperature Thermoelectric Power of Ce(Pd{1-x}Cux)2Si2 Type Journal Article
Year (up) 2015 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 179 Issue 1-2 Pages 21-27
Keywords Heavy fermions; Antiferromagnetic transition; Thermopower; Electrical resistivity
Abstract We present the thermoelectric power S(T) of the Ce(Pd 1−x Cu x ) 2 Si 2 alloy for temperatures \(1.5\,\mathrm{K} K. We observe three characteristic features across the \(0 substitution range: two positive maxima and a negative minimum, that are typical for Ce compounds that display, or lie close to, magnetism. Our analysis of the data shows that the high- T maximum is related to the Kondo effect on excited crystal-field levels, but that the low- T one cannot be simply associated with the Kondo scale, TK . We speculate that disorder induced by alloying can be at the origin of this discrepancy and can also be responsible for the low S(T) measured at low temperatures in the \(0.2 concentration range. We have extended electrical resistivity measurements on Ce(PdCu)Si 2 ( x=0.5 ) down to T∼40 mK in applied fields as high as 16 T.
Address
Corporate Author Thesis
Publisher Springer US Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 706
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Author Dolz, M.I.; Pedrazzini, P.; Pastoriza, H.; Konczykowski, M.; Fasano, Y.
Title Effect of Quenched Disorder in the Entropy-Jump at the First-Order Vortex Phase Transition of Bi{2}Sr{2}CaCu{2}O{8 + \delta } Type Journal Article
Year (up) 2015 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.
Volume 179 Issue 1-2 Pages 28-34
Keywords High Tc superconductors; First order vortex phase transition; Quenched disorder
Abstract We study the effect of quenched disorder in the thermodynamic magnitudes entailed in the first-order vortex phase transition of the extremely layered Bi 2 Sr 2 CaCu 2 O 8+δ compound. We track the temperature-evolution of the enthalpy and the entropy jump at the vortex solidification transition by means of AC local magnetic measurements. Quenched disorder is introduced to the pristine samples by means of heavy-ion irradiation with Pb and Xe producing a random columnar-track pins distribution with different densities (matching field BΦ ). In contrast with previous magneto-optical reports, we find that the first-order phase transition persists for samples with BΦ up to 100 Gauss. For very low densities of quenched disorder (pristine samples), the evolution of the thermodynamic properties can be satisfactorily explained considering a negligible effect of pinning and only electromagnetic coupling between pancake vortices lying in adjacent CuO planes. This description is not satisfactory on increasing magnitude of quenched disorder.
Address
Corporate Author Thesis
Publisher Springer US Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 707
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Author Giriat, G.; Ren, Z.; Pedrazzini, P.; Jaccard, D.
Title High pressure investigation of superconducting signatures in CeCu2Si2: ac-magnetic susceptibility, ac-heat capacity, resistivity and thermopower Type Journal Article
Year (up) 2015 Publication Solid State Communications Abbreviated Journal Solid State Commun.
Volume 209–210 Issue Pages 55-58
Keywords CeCu2Si2; Superconductivity; Magnetic susceptibility; High pressure
Abstract Taking advantage of a novel multiprobe setup we have measured, on a unique sample, the ac-magnetic susceptibility, the resistivity, the ac-specific heat and the thermopower of the superconductor heavy fermion CeCu2Si2 under pressure up to 5.1 GPa. At the superconducting transition temperature Tc, the Meissner signal corresponds to that expected for the sample volume and coincides with the specific heat jump and the resistive transition completion temperatures. Differing from previous observations, here the susceptibility measurements did not reveal any anomaly in the vicinity of the resistive transition onset.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0038-1098 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 720
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Author Sereni, J.G.; Pedrazzini, P.; Berisso, M.G.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C.
Title Local character of the highest antiferromagnetic temperature of Ce systems in Sc-rich CeTi 1− x Sc x Ge Type Journal Article
Year (up) 2015 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 91 Issue 17 Pages 174408
Keywords
Abstract The highest antiferromagnetic (AFM) temperature in Ce based compounds has been reported for CeScGe with TN=47K, but its local or itinerant nature has not been deeply investigated yet. In order to shed more light into this unusually high ordering temperature we have investigated structural, magnetic, transport, and thermal properties of CeTi1−xScxGe alloys within the range of stability of the CeScSi-type structure: 0.25≤x≤1. Along this concentration range, this strongly anisotropic system presents a complex magnetic phase diagram with a continuous modification of its magnetic behavior, from ferromagnetism for 0.25≤x≤0.50 (with 7K≤TC≤16K) to AFM for 0.60≤x≤1 (with 19K≤TN≤47K). The onset of the AFM phase is associated to a metamagnetic transition with a critical field increasing from Hcr=0 at x≈0.55 to ≈6T at x=1, coincident with an increasing contribution of the first excited crystal electric field doublet. At a critical point xcr≈0.65 a second transition appears at TL≤TN. In contrast to observations in itinerant systems like CeRh2Si2 or CeRh3B2, no evidences for significant hybridization of the 4f electrons at large Sc contents were found. Therefore, the exceptionally large TN of CeScGe can be attributed to an increasing Ruderman-Kittel-Kasuya-Yosida interaction between Ce double layers as Sc content grows.
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Corporate Author Thesis
Publisher Aps Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 716
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Author Sereni, J.G.; Pedrazzini, P.; Gómez Berisso, M.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C.
Title Exploring high temperature magnetic order in CeTi 1- x Sc x Ge Type Conference Article
Year (up) 2015 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 592 Issue 1 Pages 012005
Keywords
Abstract We studied the magnetic, transport, and thermodynamic properties of the alloy CeTi 1- x Sc x Ge in order to shed some light into the origin of the exceptionally large antiferromagnetic (AFM) ordering temperature T N = 47 K in pure CeScGe. We observed a complex magnetic phase diagram, which present an interesting dichotomy: Despite strong changes in the nature of the ordered state, from ferromagnetic (FM) for x ≤ 0.55 to AFM for x > 0.55, the ordering temperature increases smoothly and continuously from T C = 7 K at x = 0.25 to T N = 47 K at x = 1. Within the AFM regime we observe a metamagnetic transition at a critical field increasing from H = 0 at x ≈ 0.55 to μ 0 * H ≈ 6 Tesla at x = 1. Furthermore a second transition appears at T L ≤ T N for x ≥ 0.65. In contrast to observations in CeRh 2 Si 2 or CeRh 3 B 2 , we found no evidence for a strong hybridization of the 4f electrons at large Sc contents. Therefore the exceptionally large T N of CeScGe could be attributed to the unusually strong RKKY interaction in this type of compounds.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1742-6596 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 721
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Author Facio, J.I.; Betancourth, D.; Cejas Bolecek, N.R.; Jorge, G.A.; Pedrazzini, P.; Correa, V.F.; Cornaglia, P.S.; Vildosola, V.; García D.J.
Title Lattice specific heat for the RMIn5 (R=Gd, La,Y; M=Co, Rh) compounds: Non-magnetic contribution subtraction Type Journal Article
Year (up) 2016 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal J. Magn. Magn. Mater.
Volume 407 Issue Pages 406-4011
Keywords
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ victor.correa @ Serial 730
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Author Giriat, G.; Scheerer, G.W.; Ren, Z.; Pedrazzini, P.; Lapertot, G.; Jaccard, D.
Title A watchmaker’s precision at high-pressure reveals CeCu 2 Si 2 and CeAu 2 Si 2 p-T phase diagrams Type Conference Article
Year (up) 2017 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.
Volume 950 Issue 3 Pages 032008
Keywords
Abstract Gaétan Giriat and Gernot Werner Scheerer and Zhi Ren and Pablo Pedrazzini and Gerard Lapertot and Didier Jaccard
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1742-6596N2 - ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 767
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Author Encina, S.; Pedrazzini, P.; Sereni, J.G.; Geibel, C.
Title Low temperature thermopower and magnetoresistance of Sc-rich CeSc1-xTixGe Type Journal Article
Year (up) 2018 Publication Physica B: Condensed Matter Abbreviated Journal Physica B
Volume 536 Issue Pages 133-136
Keywords CeScGe; CeTiGe; Antiferromagnetism; Transport properties; Low temperatures; Magnetic field
Abstract In CeSc1-xTixGe, Ti-alloying reduces the record-high antiferromagnetic (AFM) ordering temperature found in CeScGe at TN=46K and induces ferromagnetism for x≥0.5. In this work we focus on the AFM side, i.e. Sc-rich samples, and study their thermopower S(T) and magnetoresistance ρ(H,T). The measured S(T) is small in comparison with the thermopower of other Ce-systems and shows some features that are compatible with a weak hybridization between the 4f and band states. This is a further hint pointing to the local character of magnetism in this alloy. Magnetic fields up to 16T have a minor effect on the electrical resistivity of stoichiometric CeScGe. On the other hand, for x=0.65, we find that fields above 4T suppress the hump in ρ(T). Furthermore, the 4.2K magnetoresistance displays a strong decrease in the same field range, also in coincidence with magnetization results from the literature. Our results indicate that ρ(T,H) is a proper tool to assess the H−T phase diagram of this system.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 765
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Author Fasano, Y.; Szabó, P.; Kačmarčík, J.; Pribulová, Z.; Pedrazzini, P.; Samuely, P.; Correa, V.F.
Title Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5 Type Journal Article
Year (up) 2018 Publication Physica B: Condensed Matter Abbreviated Journal Physica B
Volume 536 Issue Pages 798-802
Keywords Heavy fermion superconductors; Scanning tunneling spectroscopy; Superconducting phase; Pseudogap phase
Abstract We present scanning tunneling spectroscopy measurements of the local quasiparticles' excitation spectra of the heavy fermion CeCoIn5 between 440mK and 3K in samples with a bulk Tc=2.25K. The spectral shape of our low-temperature tunneling data, quite textbook nodal-Δ conductance, allow us to confidently fit the spectra with a d-wave density of states considering also a shortening of quasiparticles' lifetime term Γ. The Δ(0) value obtained from the fits yields a BCS ratio 2Δ/kTc=7.73 suggesting that CeCoIn5 is an unconventional superconductor in the strong coupling limit. The fits also reveal that the height of coherence peaks in CeCoIn5 is reduced with respect to a pure BCS spectra and therefore the coupling of quasiparticles with spin excitations should play a relevant role. The tunneling conductance shows a depletion at energies smaller than Δ for temperatures larger than the bulk Tc, giving further support to the existence of a pseudogap phase that in our samples span up to T*∼1.2Tc. The phenomenological scaling of the pseudogap temperature observed in various families of cuprates, 2Δ/kT*∼4.3, is not fulfilled in our measurements. This suggests that in CeCoIn5 the strong magnetic fluctuations might conspire to close the local superconducting gap at a smaller pesudogap temperature-scale than in cuprates.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 766
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Author Correa, V. F; Villagrán Asiares, A. G.; Betancourth, D.; Encina, S.; Pedrazzini, P.; Cornaglia, P.S.; García D.J.; Sereni, J. G.; Maiorov, B; Caroca-Canales, N; Geibel, Ch.
Title Strong magnetoelastic effect in CeCo1−xFexSi as Néel order is suppressed Type Journal Article
Year (up) 2019 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 100 Issue Pages 184409
Keywords
Abstract A very strong magnetoelastic effect in the CeCo1−xFexSi alloys is reported. The strength of the magnetostrictive

effect can be tuned upon changing x. The moderate low-temperature linear magnetostriction observed at low

Fe concentrations becomes very large (L

L (16T, 2K) = 3 × 10−3) around the critical concentration xc ≈ 0.23 at

which the long-range antiferromagnetic order vanishes. Upon increasing doping through the nonmagnetic region

(x > xc), the magnetostriction strength gradually weakens again. The interplay between magnetic order and the

Kondo screening appears to cause an enhanced valence susceptibility slightly changing the Ce ions valence,

ultimately triggering the large magnetostriction observed around the critical concentration. Previous studies

of the evolution of the lattice parameters with x as well as magnetization and x-ray absorption spectroscopy

measurements support this hypothesis.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ victor.correa @ Serial 842
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