D. E. Brandao

Electrical resistivity of heusler alloys

Abstract The electrical resistivity of eight different Heusler alloys is discussed in terms of electron phonon and spin-disorder scattering. The systematics common to the alloys can be explained in the intermediate to high temperature range while the low temperature range still presents interpretation difficulties.

Spontaneous magnetoimpedance in the Heusler compounds Pd2MnSn and Pd2MnSb near the Curie temperature

Abstract We report on magnetoimpedance (MI) measurements in the ferromagnetic Heusler compounds Pd 2 MnSn and Pd 2 MnSb in temperature ranges encompassing their Curie temperatures. In the ordered phase, spontaneous contributions to both the real and imaginary parts of the MI are identified below T c in experiments performed at zero applied field. Large variations of the MI are also observed when a static magnetic field is applied parallel to the current orientation.

Spin-disorder resistivity in Ni2Mn(Sn1−xInx) heusler alloys

Abstract Electrical resistivity measurements have been performed on Ni 2 Mn(Sn 1− x In x ) Heusler alloys, where x = 0, 0.02, 0.05, 0.10 and 0.15, in the temperature range of 4–300 K. The experimental data clearly show the existence of two distinct kinds of resistivity behaviour, both described by an aT n law, for 7 ⩽ T ⩽ 20 K. Between 170 and 300 K the data are well described by an AT + BT 2 phenomenological fit, and the results obtained are in good agreement with an interpretation based on electron-phonon and spin-disorder scattering.

On the preparation of copper sulphate trihydrate by a derivatograph

Copper sulphate trihydrate was prepared by dehydration from the pentahydrate sulphate by quenching the latter compound from the Derivatograph from 90 ‡C to room temperature.