Magnetic properties of (La,Gd)Al2 alloys |
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Authors: | H. v. Löhneysen J. L. Tholence F. Steglich |
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Affiliation: | (1) Centre de Recherches sur les Très Basses Températures, C.N.R.S., BP 166X, F-38042 Grenoble-Cedex, France;(2) II. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-5000 Köln 41, Federal Republic of Germany |
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Abstract: | Theac anddc susceptibilities of (La1–xGdx)Al2 alloys were measured for moderate Gd concentrations (0.01x0.08) between 0.05 and 4.2 K. Sharp spin glass like maxima inAC are observed at temperaturesTf which scale asTf/x 26 K for all samples. However, scaling ofAC is not observed indicating that the RKKY interaction at short distances which becomes more important with increasing Gd concentration, is ferromagnetic in this system. The amplitudeV0 of the RKKY interaction is obtained from both the approach to the saturation magnetization andAC forT0, yielding a mean value0=(1.5±0.3) 10–26 eV cm3 which is in agreement with that observed in other systems with Gd impurities. Furthermore, the inferred value of the exchange integral is in accord with other measurements (Tc depression, reverse resistance anomaly) on (La, Gd)Al2. A superposeddc magnetic field rounds the maximum ofAC and shifts it to lower temperatures.AC is completely flat below 4.2 K in a field which saturates the isothermal remanent magnetization, showing once again the correlation between the peak inAC and the onset of irreversible properties.This work is part of the research program of the Sonderforschungsbereich 125 Aachen/Jülich/Köln |
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