Universidad de Oviedo

Inverse Wiedemann effect in Fe-Al alloys for

torque sensing applications.

P. Bobes-Limenes, J.A. García, J. Carrizo, M. Rivas and J.C. Martínez-García

Departamento de Física. Universidad de Oviedo. Campus de Viesques, 33203 Gijón, Spain.

[1]Z.H. Liu, M Zhang, G.H. Wu, F.B. Meng, H.Y. Liu, L.Q. Yan, J.P. Qu and XY.X. Liu, Appl. Phys Lett., 85,1751

(2004)

[2]A. García-Rivas , J.M Barandiaran and J. Gutierrez, Encyclopedia of Sensors Vol X pag 1-21 (ISBN 1-58883-

056) (2006) Edited by C.A. Grimes, E.C. Dickey and M. Pishko

This work deals with the inverse Wiedemann effect (IWE) as a method to measure torque using Fe-Al alloys, especially

Fe81Al19 alloy which has been reported to have a giant magnetostriction.1 The influence of several factors has been studied

in order to maximize the sensitivity of the sensor.

The alloy under study has been fabricated in our

laboratory by melt spinning technique. A partially

crystallized structure has been obtained as it is shown in

TEM and X-ray figures.

In order to repeat measurements in a quick and precise

way, an automatic system of experimentation has been

designed with very high sensitivity using a stepper motor

controlled by a PC.

Before annealing, minimum peak is far from zero

degrees due to internal stresses.

Annealing the ribbon displaces the IWE curve,

correspondingly bringing the minimum peak to zero

degrees.

The characteristics of the current through the ribbon determine the response of the inverse Wiedemann effect.

Hc = 240 kA/m Hc = 132 kA/m

AMPLITUDE FREQUENCY

Considering the results, it seems that some

compositions could present a huge IWE related

to smaller coercivities.

Further research will be undertaken in this

direction.

Other factor that has been taken into account is the

composition of the ribbon. Measurements have been

done in ribbons with different percentage of aluminum

showing promising results.

300 nm

Grupo de Investigación

y Desarrollo de

Materiales Magnéticos

Hc = 320 kA/m