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Author (up) Berisso, M.G.; Pedrazzini, P.; Deppe, M.; Trovarelli, O.; Geibel, C.; Sereni, J.G. openurl 
  Title Composition dependence of the magnetic properties of Ge-doped CeCu2Si2 Type Journal Article
  Year 2002 Publication PHYSICA B-CONDENSED MATTER Abbreviated Journal  
  Volume 320 Issue 1-4 Pages 380-383  
  Keywords  
  Abstract Due to the proximity of CeCu2Si2 to a quantum critical point, the ground state of this compound is extremely sensitive to sample preparation conditions. Small excess of one component can lead to magnetic or superconducting behaviors. We found that in the alloy CeCu2(Si1-xGex)(2) a small excess of Ge enhances the homogeneity range allowing a precise investigation of stoichiometric effects on the physical properties. In this system, Ge doping produces an increment of the antiferromagnetic transition temperature T-N, while the superconducting one decreases. Particularly, it was found that at x = 0.1 both phases coexist at low temperature. In order to investigate the stability of these phases against changes of the Ce-ligands composition, we prepared a series of CeCu2+y(Si0.9Ge0.1)2-x, samples (0less than or equal toyless than or equal to0.10) and investigated their specific heat and electrical resistivity. We observed that the substitution of Si/Ge by Cu increases the characteristic temperature and weakens the magnetic contribution without modifying TN. A further transition, of the first order character, is observed at lower temperature. (C) 2002 Elsevier Science B.V. All rights reserved.  
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  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 ISI:000177607700103 Approved no  
  Call Number BT @ hernan @ Serial 294  
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Author (up) Deppe, M.; Caroca-Canales, N.; Sereni, J.G.; Geibel, C. url  doi
openurl 
  Title Evidence for a metamagnetic transition in the heavy Fermion system CeTiGe Type Conference Article
  Year 2010 Publication Journal of Physics: Conference Series Abbreviated Journal J. Phys.: Conf. Ser.  
  Volume 200 Issue Pages 012026  
  Keywords Applied magnetic fields; Canonical systems; Continuous suppression; Critical behavior; Critical fields; DC magnetization; First order; Heavy fermion systems; Higher temperatures; Low temperatures; Metamagnetic; Metamagnetic transitions; Polycrystalline; Cerium; Cerium compounds; Electric resistance; Magnetic field effects; Magnetoresistance; Magnetism  
  Abstract A recent study of CeTiGe identified this compound as a paramagnetic heavy Fermion system where the full J = 5/2 multiplet is involved in the formation of the ground state. Here we present a preliminary investigation of the dc-magnetization Mdc(H) and of the magnetoresistance ρ(H) of polycrystalline CeTiGe samples in applied magnetic fields up to μ0H = 14 T. The results reveal a pronounced metamagnetic transition at a critical field μ0Hc ≈ 13.5 T at low temperatures, with a step like increase in Mdc(H) of at least 0.6 μB/Ce. The metamagnetic transition leads to a strong decrease in ρ(H). A clear hysteresis in Mdc(H) and ρ(H) indicate that in CeTiGe these metamagnetic features correspond to a true thermodynamic, first order type transition in contrast to the critical behavior observed in the canonical system CeRu2Si2. Measurements at higher temperatures showed a continuous suppression of the metamagnetic transition with increasing T, which vanishes at T ∼ 30 K. © 2010 IOP Publishing Ltd.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Karlsruhe Editor  
  Language Summary Language Original Title  
  Series Editor Series Title International Conference on Magnetism, ICM 2009 Abbreviated Series Title  
  Series Volume 200 Series Issue SECTION 1 Edition  
  ISSN 17426588 (ISSN) ISBN Medium  
  Area Expedition Conference  
  Notes Conference code: 81773; Export Date: 10 December 2010; Source: Scopus; Art. No.: 012026; doi: 10.1088/1742-6596/200/1/012026; Language of Original Document: English; Correspondence Address: Deppe, M.; Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany; email: Hicha.Deppe@cpfs.mpg.de; References: Gegenwart, P., Si, Q., Steglich, F., (2008) Nature Phys., 4 (3), p. 186; Sachdev, S., (2008) Nature Phys., 4 (3), p. 173; Blundell, S., (2001) Oxford Master Series in Condensed Matter Physics, , (Oxford University Press); Monthoux, P., Lonzarich, G.G., (2001) Phys. Rev., 63 (5), p. 054529; Morozkin, A.V., Seropegin Yu, D., Leonov, A.V., Sviridov, I.A., Tskhadadze, I.A., Nikitin, S.A., (1998) J. Alloys Comput., 267, pp. 14-15R; Welter, R., Vernière, A., Venturini, G., Malaman, B., (1999) J. Alloys. Compounds, 283 (1-2), p. 54; Deppe, M., Caroca-Canales, N., Hartmann, S., Oeschler, N., Geibel, C., (2009) J. Phys.: Condens. Matter, 21 (20), p. 206001; Hewson, A.C., (1993) The Kondo Problem to Heavy Fermions (Cambridge Studies in Magnetism), 2. , ed D Edwards and D Melville (Cambridge: Cambridge University press); Haen, P., Flouquet, J., Lapierre, F., Lejay, P., Remenyi, G., (1987) J. Low Temp. Phys., 67 (5-6), p. 391; Sakakibara, T., Tayama, T., Matamura, K., Maezawa, K., Onuki, Y., Amitsuka, H., (1995) Phys. Rev., 51 (17), p. 12030; Andreev, A.V., Vejpravov, J., ProkleÅ¡ka, J., Sechovsky, V., (2008) Physica, 403 (5-9), p. 744 Approved no  
  Call Number BT @ berisso @ Serial 599  
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Author (up) Deppe, M.; Pedrazzini, P.; Caroca-Canales, N.; Gelbel, C.; Sereni, J.G. openurl 
  Title Investigations of CePd1-xRhx single crystals located near a ferromagnetic quantum critical point Type Journal Article
  Year 2006 Publication PHYSICA B-CONDENSED MATTER Abbreviated Journal  
  Volume 378-380 Issue Pages 96-97  
  Keywords  
  Abstract Investigations of CePd1-xRhx polycrystals have revealed a continuous transition from a ferromagnetic state at x = 0 to an intermediate valence state at x = 1 and evidenced non-Fermi liquid behavior near the critical concentration x(c) approximate to 0.85 where T-C is continuously suppressed to T = 0 K. We present here first results of specific heat and magnetization measurements on CePd1-xRhx single crystals with composition close to the critical point. They confirm the results obtained on polycrystals and reveal a rather low magnetic anisotropy, despite the orthorhombic structure. (c) 2006 Elsevier B.V. All rights reserved.  
  Address  
  Corporate Author Thesis  
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  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 ISI:000238426600033 Approved no  
  Call Number BT @ hernan @ Serial 56  
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Author (up) Hartmann, S.; Deppe, M.; Oeschler, N.; Caroca-Canales, N.; Sereni, J.G.; Geibel, C. openurl 
  Title Ferromagnetism in CePd1-xRhx single crystals Type Journal Article
  Year 2008 Publication Journal of Optoelectronics and Advanced Materials Abbreviated Journal J. Optoelectr. Adv. Mater.  
  Volume 10 Issue 7 Pages 1607-1611  
  Keywords Ce compound, ferromagnetism, heavy fermion system  
  Abstract The orthorhombic CePd1-xRhx alloy exhibits a continuous evolution from a ferromagnetic ground state at x = 0 to

intermediate-valence behavior for x = 1. Here, we report on specific heat CP(T), resistivity ρ(T) and magnetization M(T)

measurements on single crystals in a Rh concentration range 0.2 < x < 0.65 exploring the ferromagnetic side of the

magnetic phase diagram. The transport and thermodynamic properties of the ferromagnetic phase have been investigated

in the temperature range from 300 K down to 0.35 K and analyzed in terms of a gap in the magnon spectrum and an

underlying Kondo contribution. Crystal electric field parameters are deduced from specific heat measurements well above

Tc- The competition between Kondo effect and ferromagnetism has been studied in dependence of the Rh concentration in

the system. Particularly, the enhanced Sommerfeld coefficient γ(x) indicates strong Kondo interactions when the Curie

temperature is reduced.		  
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  Call Number BT @ hernan @ Serial 308  
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Author (up) Pedrazzini, P.; Berisso, M.G.; Caroca-Canales, N.; Deppe, M.; Geibel, C.; Sereni, J.G. doi  openurl
  Title Low temperature magnetic phase diagram of the cubic non-Fermi liquid system Celn(3-x)Sn(x) Type Journal Article
  Year 2004 Publication The European Physical Journal B – Condensed Matter Abbreviated Journal Eur. Phys. J. B  
  Volume 38 Issue 3 Pages 445-450  
  Keywords  
  Abstract In this paper we report a comprehensive study of the magnetic susceptibility (x), resistivity (p), and specific heat (C-P), down to 0.5 K of the cubic CeIn3-xSnx alloy. The ground state of this system evolves from antiferromagnetic (AF) in CeIn3 (T-N = 10.2 K) to intermediate-valent in CeSn3, and represents the first example of a Ce-lattice cubic non-Fermi liquid (NFL) system where T-N(x) can be traced down to T = 0 over more than a decade of temperature. Our results indicate that the disappearance of the AF state occurs near x(c) approximate to 0.7, although already at x approximate to 0.4 significant modifications of the magnetic ground state are observed. Between these concentrations, clear NFL signatures are observed, such as rho(T) approximate to rho(0) + A T-n (with n < 1.5) and C-P(T) proportional to -T ln(T) dependencies. Within the ordered phase a first order phase transition occurs for 0.25 < x < 0.5. With larger Sn doping, different weak rho(T) dependencies are observed at low temperatures between x = 1 and x = 3 while C-P/T shows only a weak temperature dependence.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6028 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000222309400006 Approved no  
  Call Number BT @ hernan @ Serial 289  
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Author (up) Pedrazzini, P.; Berisso, M.G.; Caroca-Canales, N.; Deppe, M.; Geibel, C.; Sereni, J.G. openurl 
  Title Non-Fermi liquid behaviour in cubic CeIn3-xSnx Type Journal Article
  Year 2002 Publication PHYSICA B-CONDENSED MATTER Abbreviated Journal  
  Volume 312 Issue Pages 406-407  
  Keywords  
  Abstract The alloy between the antiferromagnetic (AF) CeIn3 and the mixed valent CeSn3 is particularly interesting since it is one of the few cases where a magnetic to non-magnetic transition is observed in a cubic system. Although the resulting alloy CeIn3-xSnx has been investigated for over 20 years, no information is available about thermodynamic and transport properties below 2K. We report first measurements on resistivity rho(T) and specific heat C-P(T) down to 0.45 K. These results confirm the disappearance of the AF state near xcongruent to0.6. In samples close to this critical concentration, we observe a strong departure from the Fermi liquid behaviour, i.e. rho(T) approximate to rho(0) + a T-n (n < 1.5) and a logarithmic temperature dependence C-P(T)infinity – T ln (T), in more than a decade above the lowest investigated temperature. (C) 2002 Elsevier Science B.V. All rights reserved.  
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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 ISI:000175871000148 Approved no  
  Call Number BT @ hernan @ Serial 72  
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Author (up) Pedrazzini, P.; Berisso, M.G.; Sereni, J.G.; Caroca-Canales, N.; Deppe, M.; Geibel, C. openurl 
  Title Complex magnetic phase diagram near the quantum critical point in CeIn3-xSnx Type Journal Article
  Year 2003 Publication ACTA PHYSICA POLONICA B Abbreviated Journal  
  Volume 34 Issue 2 Pages 363-366  
  Keywords  
  Abstract A recent reinvestigation of the alloy system CeIn3-xSnx between the antiferromagnetic (AF) Kondo-lattice CeIn3 and the intermediate valent CeSn3 has shown that the AF order disappears at a quantum critical point (QCP) at x(c) approximate to 0.65. Preliminary evidences for a first order transition below T-N at x < x(c), indicating a complex magnetic phase diagram, have motivated the present detailed investigation of specific heat and resistivity on fine tuned samples in the 0.25 less than or equal to x less than or equal to x(c) range. These results confirm the first order transition at T-I < T-N in a reduced concentration range (0.25 < x < 0.47) and suggest that the phase boundary T-I (x) merge with the T-N(x) near x approximate to 0.37, leading to a tetracritical point. A similar first order transition was previously observed in the CeCu2(Si,Ge)(2) system at low Ge-concentration. Since in this alloy the first order transition also appears in the vicinity of a QCP, the question arises concerning how general this property is at AF critical points in Ce-based alloy systems.  
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  ISSN 0587-4254 ISBN Medium  
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  Notes ISI:000181544200011 Approved no  
  Call Number BT @ hernan @ Serial 292  
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Author (up) Pedrazzini, P.; Jaccard, D.; Deppe, M.; Geibel, C.; Sereni, J.G. url  doi
openurl 
  Title Multiprobe high-pressure experiments in CePd0.6Rh0.4 and CePd3 Type Journal Article
  Year 2009 Publication Physica B: Condensed Matter Abbreviated Journal Physica B  
  Volume 404 Issue 19 Pages 2898-2903  
  Keywords Ce compounds; Ferromagnetism; Quantum phase transition; High pressure; Resistivity; Seebeck coefficient; Specific heat  
  Abstract Results of recent multiprobe high-pressure experiments on ferromagnetic CePd0.6Rh0.4 and intermediate-valent CePd3 are presented. Simultaneous resistivity (ρ), thermopower (S), and ac heat capacity measurements show that the long-range ferromagnetic state of CePd0.6Rh0.4 vanishes in the proximity of a sharp valence-crossover pressure , i.e. before reaching a quantum critical point. However, a magnetic signal that is progressively suppressed is still detected at higher pressures. For CePd3, the results of simultaneous ρ(T,p) and S(T,p) measurements up to and down to the mK temperature range show a surprisingly weak pressure dependence.  
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  ISSN 0921-4526 ISBN Medium  
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  Notes Approved no  
  Call Number BT @ jsereni @ Serial 561  
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Author (up) Pikul, A.P.; Caroca-Canales, N.; Deppe, M.; Gegenwart, P.; Sereni, J.G.; Geibel, C.; Steglich, F. doi  openurl
  Title Non-Fermi-liquid behaviour close to the disappearance of ferromagnetism in CePd1-xRhx Type Journal Article
  Year 2006 Publication Journal of Physics: Condensed Matter Abbreviated Journal J. Phys.: Condens. Matter.  
  Volume 18 Issue 42 Pages L535-L542  
  Keywords  
  Abstract The orthorhombic CePd1- xRhx system exhibits a continuous evolution from ferromagnetic order in CePd ( T-C = 6.6 K) to an intermediate-valence ground state in CeRh. Here we report low-temperature ( T >= 0.08 K) specific-heat measurements for concentrations 0.80 <= x <= 0.95 close to the disappearance of magnetic order (similar to 0.87). In contrast to x = 0.8, still demonstrating a smeared phase transition signature at 0.27 K, non-Fermi-liquid behaviour Delta C(T) / T alpha log T is observed in the electronic specific-heat coefficient at x = 0.85. For higher Rh concentrations a weak power-law dependence Delta C(T) / T alpha T-alpha with alpha approximate to 0.4 is found. Upon applying magnetic fields Fermi-liquid-like behaviour Delta C(T) / T similar to const is recovered in all the different samples. The magnetic entropy as well as the concentration of unscreened magnetic moments at 2 K indicate a broad distribution of local T-K values ranging from well below 2 K to far above 50 K.  
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  ISSN 0953-8984 ISBN Medium  
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  Notes ISI:000241278000001 Approved no  
  Call Number BT @ hernan @ Serial 54  
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Author (up) Sereni, J.G.; Gomez Berisso, M.; Canales, N.C.; Deppe, M.; Geibel, C. url  openurl
  Title Tuning ground state degeneracy and quantum criticality in Ce1-xLaxTiGe Type Journal Article
  Year 2010 Publication Physica Status Solidi (B) Basic Research Abbreviated Journal Phys. Status Solidi B Basic Res.  
  Volume 247 Issue 3 Pages 707-709  
  Keywords  
  Abstract We have tuned the paramagnetic heavy Fermion (HF) system CeTiGe to a more magnetic state and toward quantum criticality (QC) by partially substituting La for Ce. The induced volume expansion leads to a pronounced decrease of the Kondo temperature (TK), from ≈50 K in pure CeTiGe to less than 4 K at large La content. Since the former value is of the order of the crystal field splitting, while the latter is well below, the systems evolves from a large degeneracy N = 6 Kondo system at x = 0 to a conventional N = 2 Kondo system at x ≥ 0:8. There, the first excited crystal field doublets become apparent in the T dependence of the specific heat CP(T) at an excitation energy DCF ≈ 30 K. The reduction of the degeneracy is expected to enhance the decrease of TK, explaining the strong reduction by more than one order of magnitude observed in this system. The decrease of TK drives the system toward QC as evidenced by a divergence of CP(T)/T and x(T) toward low temperatures in the x = 0:8 sample. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.  
  Address Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany  
  Corporate Author Thesis  
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  ISSN 03701972 (ISSN) ISBN Medium  
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  Notes Export Date: 1 June 2010; Source: Scopus; doi: 10.1002/pssb.200983029; Language of Original Document: English; Correspondence Address: Sereni, J.G.; Low Temperature Laboratory, Centro Atómico Bariloche (CNEA), 8400 S. C. Bariloche, Argentina; email: jsereni@cab.cnea.gov.ar; References: Löhneysen, H.v., Rosch, A., Vojta, M., Wölfle, P., (2007) Rev. Mod. Phys., 79, p. 1015; Welter, R., Venturini, G., Malamann, B., (1992) J. Alloys Compd, 189, p. 49; Deppe, M., Caroca-Canales, N., Hartmann, S., Oeschler, N., Geibel, C., (2009) J. Phys. Condens. Matter, 21, p. 206001; Deppe, M., Caroca-Canales, N., Sereni, J.G., Geibel, C., (2010) J. Phys.:Condens. Matter, , accepted; Stewart, G.R., (2006) Rev. Mod. Phys., 78, p. 743; Schlottmann, P., (1984) Phys. Rev. B, 30, p. 1454; Desgranges, H.U., Rasul, J.W., (1987) Phys. Rev. B, 36, p. 328 Approved no  
  Call Number BT @ berisso @ Serial 594  
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