Simultaneous Measurement of Magnetization and Magnetostriction in CeRu₂Si₂ at Very Low Temperatures: A Test of the One-Parameter Scaling Property

Simultaneous measurements of the magnetization M and the magnetostriction λ of a high quality single crystal of CeRu₂Si₂ were performed at temperatures down to 70 mK in magnetic fields H up to 85 kOe, in order to test the validity of the scaling conjecture M ∼ Φ[H/H_s(P)] around the metamagnetic crossover at very low temperatures. Here H_s is a characteristic field and P is the pressure. By use of a thermodynainic equality and the scaling relation. λ(H) is calculated from the magnetization data M(H). For various temperatures below 4.2 K, the calculated results could be fitted to the experimental data of λ(H) remarkably well with only the single parameter Ω ≡ ∂ ln H_s/∂P ≈ 200 Mbar^-1, well confirming the scaling relation even at very low temperatures where metamagnetism becomes quite sharp. It is inferred that the metamagnetic behavior of this system is governed by a single energy scale. We have also estimated the constant-volume (V) magnetization curve at T = 70 mK from the experimentally observed constant pressure (P = 0) curve, using the scaling relation. The result shows that the constant-V magnetization process still exhibits metamagnetism, although much broadened in the absence of the magneto-volume effect.