Mechanical control of magnetic properties in magnetostrictive thin films offers the unexplored opportunity to employ surface wave acoustics in such a way that dynamic magnetic effects are triggered. Strain-induced modulation of the magnetic anisotropy can play a role in high-frequency varying effective magnetic fields, leading to ultrasonic tuning of electronic and magnetic properties of nanostructured materials, which eventually can be integrated into semiconductor technology. Here, we report on the opportunity to employ surface acoustic waves to trigger magnetocaloric effects in MnAs(100 nm)/GaAs(001) thin films. During the MnAs magnetostructural phase transition, in an interval range around room temperature (0${}^{\circ }$–60 ${}^{\circ }$C), ultrasonic waves (170 MHz) are strongly attenuated by the phase coexistence (up to 150 dB/cm). We show that the giant magnetocaloric effect of MnAs is responsible for the observed phenomenon. By use of a simple anelastic model we describe the temperature and the external magnetic field dependence of such a huge ultrasound attenuation. Strain manipulation of the magnetocaloric effect could be a further interesting route for dynamic and static caloritronics and spintronics applications in semiconductor technology.

• Received 31 January 2012

DOI:https://doi.org/10.1103/PhysRevB.86.035207