Quantum critical behaviour in the CePd2Si2/CeNi2Ge2 system |
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Authors: | S J S Lister F M Grosche F V Carter R K W Haselwimmer S S Saxena N D Mathur S R Julian G G Lonzarich |
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Institution: | 13. Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, UK
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Abstract: | We have explored the vicinity of the antiferromagnetic quantum critical point in the related heavy fermion metals CePd2Si2 and CeNi2Ge2 as a function of hydrostatic pressure. The normal state resistivity of the antiferromagnet CePd2Si2 near the critical pressure, at which magnetic order disappears, varies as ρ ~ Tχ(1:1 < χ < 1:4) over nearly two orders of magnitude in temperature up to about 30 K. This anomalous form for the resistivity appears to defy not only Fermi-liquid theory, but also simple phenomenological models for the effect of spin fluctuations close to a quantum critical point. An analogous unconventional behaviour is observed in the ambient pressure resistivity of the electronically and structurally equivalent, non-magnetic metal CeNi2Ge2. At pressures above 15 kbar, a new and unexpected superconducting transition appears in CeNi2Ge2 below 220 mK, which rises to higher temperatures with increasing pressure, reaching 400 mK at 26 kbar. |
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