Piezostrain modulation of magnetic damping in MBE-grown epitaxial Co₂FeAl/GaAs heterostructure

The electric voltage manipulated magnetic dynamic properties of Co₂FeAl/GaAs heterostructure bonded on PbZr_1−xTi_xO₃ piezoelectric substrate were investigated using the time-resolved magneto-optical Kerr effect technique at room temperature. The butterfly-like response of precession frequency dependence on the applied electric field was observed with no external magnetic field applied, indicating efficient manipulation of precession frequency solely by piezostrain. The magnetic damping of Co₂FeAl was observed to be enhanced (decreased) under the strengthened compressive (tensile) strain modulation. The observed efficient tuning of both precession frequency and extrinsic damping constant at low magnetic fields is attributed to piezostrain modulated magnetic anisotropy value and its inhomogeneous distribution. When the magnetic dynamics is governed by the external magnetic field at high-field regime, electric field tunability of precession frequency and damping constant becomes weaker and the intrinsic damping constant shows no modulation. The electric voltage tuning of magnetic damping and the associated physical mechanism presented in this work can help designing strain-mediated low-energy cost spintronic devices. (paper)