Spin-Glass Transition in a Magnetic Field for Canonical Spin Glasses AuFe and AgMn and the Critical Phenomena

A magnetic field vs temperature ( H - T ) phase diagram is determined from linear χ ⊥ 0 and nonlinear χ ⊥ 2 susceptibilities perpendicular to H for metallic spin glasses AuFe (4 at.%Fe) and AgMn (4 at.%Mn). Two characteristic temperatures T 1 ( H ) and T 2 ( H ) in the H - T phase diagram are obtained from the measurements of χ ⊥ 0 and χ ⊥ 2 . The σ ⊥ 2 signal has a round maximum at T = T 1 ( H ) and below T 1 ( H ) the imaginary part of χ ⊥ 0 increases rapidly around T = T 2 ( H ). The critical exponents β and γ are found to be β=1.0±0.2, γ=2.0±0.2 for AuFe (4at.%Fe) and β=1.0±0.2, γ=1.7±0.2 for AgMn (4 at.%Mn) from the scaling argument. Nonlinear magnetization far above T g is discussed with the Sherrington-Kirkpatrick (SK) model including an additional atomic short-range effect.