Electric-Field Modulation of Perpendicular Magnetic Anisotropy and Damping Constant in MgO/Co/Pt Trilayers

Electric field modulations of the perpendicular magnetic anisotropy (PMA) and magnetization dynamics of MgO/Co/Pt trilayers were measured by time-resolved magneto-optical Kerr effect (TRMOKE). The anisotropy field estimated from the anomalous Hall effect applying a field along in-plane was confirmed to be modified by the electric field, which results in the PMA variation with an electric field of −32 fJ/(
$\text{V}\cdot \text{m}$
). The PMA variation was also confirmed from TRMOKE measurements, which was estimated to be −47 fJ/(
$\text{V}\cdot \text{m}$
). From TRMOKE measurements, we also observed the reduction of the inverse of relaxation time 1/
$\tau $
of the magnetization precession with increasing the electric field. The 1/
$\tau $
was analyzed by assuming the contributions of effective Gilbert damping
$\alpha _{\text {eff}}$
, anisotropy distribution, anisotropy angle distribution, and two magnon scattering, and we found
$\alpha _{\text {eff}}$
decreased with increasing the electric field whose modulation was −0.0046 nm/V, corresponding to −13% per 1 V/nm. These results are similar to the electric field effect in (001)-orientated MgO/CoFeB/Ta trilayers, however, our finding indicates similar PMA and
$\alpha $
modulations are found in MgO/Co/Pt trilayers having MgO(111)/fcc-Co interface.