The field of magnonics is emerging at blistering pace due to its promising room-temperature applications in logic-based devices at low-power consumption. In view of this,
the exploration of suitable ferromagnetic (FM) La0.67Sr0.33MnO3
(LSMO) and ferroelectric (FE) Pb(Mg0.33Nb0.67)O3-PbTiO3(PMN-PT) magnetoelectric (ME) heterostructures is of
prime interest due to their intimate interface contact 1.
In the present work, a 50-nm-thick LSMO was grown on PMN-PT(001) and PMN-PT(111) single crystals by using pulsed laser deposition. The epitaxial nature of LSMO is confirmed by
x-ray diffraction data. The static and dynamic magnetic response of LSMO/PMN-PT is studied by performing magnetization (M) and ferromagnetic resonance (FMR) measurements. Due
to strong ME coupling at the interface, the LSMO/PMN-PT(001) shows four-fold symmetry of magnetic anisotropy (MA) whereas LSMO/PMN-PT(111) shows isotropic behaviour (see
Fig. 1). The observation can be interpreted on the basis of coupling between the resultant polarisations of PMN-PT and the net M vector of LSMO 2. To know the effect of ME-induced
MA on the magneto-dynamic response of LSMO, FMR measurements were carried. The FMR data are fitted with the Kittel’s equation and obtained the Gilbert damping constant (α),
which is a key parameter for spin-wave (SW) dynamics, is in the order of 10-2. As the LSMO/PMN-PT(001) is anisotropic in nature, α is found to be smaller along the hard axis than the
easy direction. On the other hand, the LSMO/PMN-PT(111) is isotropic in nature, so that the α remains same in all directions. In order to explore the electric (E-) field effect on the spin
dynamics, FMR data are collected for the LSMO/PMN-PT poled (E = ±10 kV/cm) samples, where a significant reduction in α values is seen. From these combined results, we conclude
that α depends strongly on MA of the films other than its surface roughness, defects, etc. 3. Although more investigations are required, this particular work hints that it becomes possible
to realize E-field controlled SWs in FM/FEs to develop futuristic magnonic devices.
1 D. Pesquera, E. Khestanova, M. Ghidini, S. Zhang, A. P. Rooney, F. Maccherozzi, P. Riego, S. Farokhipoor, J. Kim, X. Moya, M. E. Vickers, N. A. Stelmashenko, S. J.
Haigh, S. S. Dhesi, and N. D. Mathur, Nat. Commun. 11, 3190 (2020).
2 G. Venkataiah, Y. Shirahata, M. Itoh, and T. Taniyama, Appl. Phys. Lett. 99, 102506 (2011). 3 K. Yamada, K. Kogiso, Y. Shiota, M. Yamamoto, A. Yamaguchi, T. Moriyama, T. Ono, and M. Shima, J. Magn. Magn. Mater. 513, 167253 (2020).
Fig.1. The polar plots of normalized remanent magnetization (Mr/Ms) of (a) LSMO/PMN-PT(001) and (b) LSMO/PMN-PT(111) heterostructures.