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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. doi  openurl
  Title Strong magnetoelastic effect in CeCo1−xFexSi as Néel order is suppressed Type Journal Article
  Year 2019 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 100 Issue Pages (down) 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.
 
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  Notes Approved no  
  Call Number BT @ victor.correa @ Serial 842  
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Author Sereni, J.G.; Pedrazzini, P.; Berisso, M.G.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C. openurl 
  Title Local character of the highest antiferromagnetic temperature of Ce systems in Sc-rich CeTi 1− x Sc x Ge Type Journal Article
  Year 2015 Publication Physical Review B Abbreviated Journal Phys. Rev. B  
  Volume 91 Issue 17 Pages (down) 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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  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 716  
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Author Carreras Oropesa, W.G.; Encina, S.; Pedrazzini, P.; Correa, V.F.; Sereni, J.G.; Vildosola, V.; García D.J.; Cornaglia, P.S. doi  openurl
  Title Minimal model for the magnetic phase diagram of CeTi1-xScxGe, GdFe1-xCoxSi, and related materials Type Journal Article
  Year 2020 Publication Journal of Magnetism and Magnetic Materials Abbreviated Journal  
  Volume 503 Issue Pages (down) 166614  
  Keywords Magnetism; RTX  
  Abstract We present a theoretical analysis of the magnetic phase diagram of CeTi1-xScxGe and GdFe1-xCoxSi as a function

of the temperature and the Sc and Co concentration x, respectively. CeScGe and GdCoSi, as many other RTX

(R=rare earth, T=transition metal, X=p-block element) compounds, present a tetragonal crystal structure

where bilayers of R are separated by layers of T and X. While GdFeSi and CeTi0.75Sc0.25Ge are ferromagnetic,

CeScGe and GdCoSi order antiferromagnetically with the R 4f magnetic moments on the same bilayer aligned

ferromagnetically and magnetic moments in nearest neighbouring bilayers aligned antiferromagnetically. The

antiferromagnetic transition temperature TN decreases with decreasing concentration x in both compounds and

for low enough values of x the compounds show a ferromagnetic behavior. Based on these observations we

construct a simplified model Hamiltonian that we solve numerically for the specific heat and the magnetization.

We find a good qualitative agreement between the model and the experimental data. Our results show that the

main magnetic effect of the Sc→Ti and Co→Fe substitution in these compounds is consistent with a change in

the sign of the exchange coupling between magnetic moments in neighbouring bilayers. We expect a similar

phenomenology for other magnetic RTX compounds with the same type of crystal structure.
 
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  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ victor.correa @ Serial 856  
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Author Sereni, J.G.; Pedrazzini, P.; Gómez Berisso, M.; Chacoma, A.; Encina, S.; Gruner, T.; Caroca-Canales, N.; Geibel, C. url  doi
openurl 
  Title Exploring high temperature magnetic order in CeTi 1- x Sc x Ge Type Conference Article
  Year 2015 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.  
  Volume 592 Issue 1 Pages (down) 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.  
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  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 Encina, S.; Pedrazzini, P.; Sereni, J.G.; Geibel, C. url  doi
openurl 
  Title Low temperature thermopower and magnetoresistance of Sc-rich CeSc1-xTixGe Type Journal Article
  Year 2018 Publication Physica B: Condensed Matter Abbreviated Journal Physica B  
  Volume 536 Issue Pages (down) 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.  
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  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 Encina, S.; Pedrazzini, P. url  openurl
  Title Poder termoeléctrico del Ce(Pd1-xCux)2Si2 Type Conference Article
  Year 2013 Publication Anales de la Asociacion Fisica Argentina Abbreviated Journal Anales AFA  
  Volume 24 Issue 2 Pages (down) 43-46  
  Keywords poder termoeléctrico, resistividad eléctrica, bajas temperaturas, CePd 2Si2, CeCu2Si2, temperatura de Kondo, campo cristalino, compuestos de Ce, magnetismo  
  Abstract Se presenta un estudio del poder termoeléctrico, S(T), a bajas temperaturas de la aleación Ce(Pd1-xCux)2Si2. Las curvas deS(T) tienen una dependencia similar en todo el rango de sustitución, con tres anomalías: un máximo positivo de altatemperatura, un mínimo negativo y un máximo de bajas temperaturas. Se discute brevemente el origen de las anomalías,para lo cual se compara S(T) con datos de resistividad eléctrica provenientes de la literatura. Para realizar las medicionesde poder termoeléctrico se diseñó y construyó un dispositivo que puede ser montado en diversos crióstatos.  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number BT @ pedrazp @ Serial 674  
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Author Encina, S.; Pedrazzini, P. doi  openurl
  Title Low Temperature Thermoelectric Power of Ce(Pd{1-x}Cux)2Si2 Type Journal Article
  Year 2015 Publication Journal of Low Temperature Physics Abbreviated Journal J. Low Temp. Phys.  
  Volume 179 Issue 1-2 Pages (down) 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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