Magneto-Optical Study of Martensitic Transition in Ni_(45)Mn_(36.7)In_(13.3)Co_5 (at.) Single Crystals

摘要

Transverse Kerr effect (TKE) was used to study magneto-optical (MO) properties of Ni_(45)Mn_(36.7)In_(13.3)Co_5 (at.%) single crystals. A single crystalline ingot of such composition was grown by the Czochralski method. One series of samples was quenched into cold water (WQ) and the other series after quenching was heated at 770 K for 20 min and slowly cooled to assure a complete atomic order (SC). Accordingly to differential scanning calorimetry (DSC), magnetic and magneto-optical (MO) measurements, WQ samples exhibit well-defined martensitic transition (MT), but the SC samples do not show MT. It is found that TKE for WQ samples shows the following features (i) MO signal is well pronounced far below the martensitic transition in spite of a weak magnetization of martensitic phase; (ii) the characteristic temperatures of martensitic transition differ from those for the bulk and depend on annealing conditions; (iii) MO spectra profile do not change significantly during the martensitic transition and is similar but not identical with that for Ni_(50)Mn_(35)In_(15) thin films and Ni_(43.7)Mn_(43.6)In_(12.7) ribbons measured before; (iv) MO signal is anisotropic.