Nanocomposites and nanomaterials

Stress sensitivity of nanolayered magnetic sensors
Sohatsky V.P., Zubenko I.A., Pokutnii O.Y.
 T. Shevchenko National University of Kyiv, 60 Volodymyrska Str., 01601, Ukraine. 
E-mail: vso@univ.kiev.ua   

   
Fig.1. Hysteresis loops for various directions of
 applied mechanical stress:
UP= a)-130 V; b) 0 V; 
c) +70V;  d) +130V.

Film nanostructures with magnetically interacting metal layers are promising functional elements of spintronics, which can function even on the bending substrates. It is possible to change characteristics of such elements by applying a mechanical stress. Therefore studying of the remagnetization curves dependence on magnitude of mechanical stress is important for determining the main properties of material as well as for adjustment performance of these elements. We present the results of magneto-optical observations of magnetic hysteresis loop shapes from close to linear (Fig.1a) till almost stepped discrete (d). These changes occure under mechanical stresses of different magnitude or direction and can be used for changing of sensor operating mode. 
Simulation of such a remagnetization was performed on a basis of the Stoner-Wolfart energy balance model with the additional component EU(φ,θ), responsible for deformation

and coefficients, that take into account a correlation between exchange interactions and magneto-static. Thus calculated "piezomagnetic" hysteresis loops usually coincided with the experimental ones, obtained by means of magneto-optical Kerr effect.
Our modelling allowed not only to determine the magnetic states of the spin elements under different external influence, but also to determine parameters of the nanolayers, that were the components of the spin-valves. 
Thereby a deformation sensitivity could be changing by changing a direction of deformation in the film plane both with or without applying of the external magnetic field.