Differential magnetostrictive response in magnetically annealed Tb _0.36Dy_0.64(Fe_0.85Co_0.15) ₂ with 〈110〉 crystal orientation

Magnetic heat treatment has been carried out on a giant magnetostrictive alloy Tb0.36 Dy0.64 (Fe0.85 Co0.15) 2 with 〈110〉 crystal orientation. A dramatic improvement in magnetostriction along and perpendicular to the crystal axis (defined as λ∥ and λ⊥, respectively) occurs when cooling the sample through the Curie temperature TC under 240 kAm applied perpendicular to its axis. When the applied annealing field was parallel to the crystal axis, the magnetostrictive behavior becomes "anomalous;" negative λ∥ and positive λ⊥ are obtained in low fields, accompanied with relatively low values in high fields. A single-{111}-twin model has been suggested to explain such differential magnetostrictive response.