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M Ocio

Publications and source records attributed to M Ocio.

3 recordsLinked to original sources
PubMed2002

Fluctuation-dissipation ratio of a spin glass in the aging regime.

We present the first experimental determination of the time autocorrelation C(t',t) of magnetization in the nonstationary regime of a spin glass. Quantitative comparison with the response, the magnetic susceptibility chi(t',t), is made by using a new experimental setup allowing both measurements in the same conditions. Clearly, we observe a nonlinear fluctuation-dissipation relation between C and chi, depending weakly on the waiting time t'. Following theoretical developments on mean-field models, and lately on short range ones, it is predicted that in the limit of long times the chi(C) relationship should become independent of t'. A scaling procedure allows us to extrapolate to the limit of long waiting times.

Journal Article↗
PubMed2001

Non-fermi-liquid scaling in Ce(Ru0.5Rh)2Si2.

We study the temperature and field dependence of the magnetic and transport properties of the non-Fermi-liquid (NFL) compound Ce(Ru0.5Rh0.5)2Si2. For fields H less, similar0.1 T the results suggest that the observed NFL behavior is disorder driven. For higher fields, however, magnetic and transport properties are dominated by the coupling of the conduction electrons to critical spin fluctuations. The temperature dependence of the susceptibility as well as the scaling properties of the magnetoresistance are in very good agreement with the predictions of recent dynamical mean-field theories of Kondo alloys close to a spin-glass quantum critical point.

Journal Article↗