Spannungsinduzierte Crossover-Effekte in der Nähe des Curiepunkts von nickel

Abstract

Stress-induced crossover effect near the Curie point of nickel I. Experimental details and results

In a small angle neutron scattering experiment stress-induced crossover in a ferromagnetic nickel single crystal was observed. The crossover effect was measured with applied tensile stresses of [sgrave]=0–140 p/mm²† parallel to the ⟨111⟩ direction of the Ni crystal. The variation of temperature was about T _c ± 15 K and excellent temperature stability was obtained (ΔT/Δt < 0·01 K/h, ΔT/Δx < 0·01 K/mm). The important quantity T _c was determined simultaneously by three independent methods. The crossover temperature τ _g =(8·5 ± 2) × 10⁻⁵ (τ=(T – T _c)/T _c) was obtained from the method of the effective critical exponent νv _eff. The critical exponent of the longitudinal correlation length could be determined as ν_is=0·63±0·03 in the isotropic temperature range (τ > τ _g ) and as v _an=0·52 ± 0·04 in the anisotropie range (τ < τ _g ). Further critical parameters are γ = 1·32 ± 0·05 and η = 0·052 ± 0·015.