  We have explored the electric field controlled magnetization in the nanodot
CoFe2O4/SrRuO3/PMN-PT heterostructures. Ordered ferromagnetic CFO nanodots
(~300 nm lateral dimension) are developed on the PMN-PT substrate
(ferroelectric as well as piezoelectric) using a nanostencil-mask pattering
method during pulsed laser deposition. The nanostructures reveal electric field
induced magnetization reversal in the single domain CFO nanodots through
transfer of piezostrains from the piezoelectric PMN-PT substrate to the CFO.
Further, electric field modulated spin structure of CFO nanomagnets is analysed
by using X-ray magnetic circular dichroism (XMCD). The XMCD analysis reveals
cations (Fe3+/Co2+) redistribution on the octahedral and tetrahedral site in
the electric field poled CoFe2O4 nanodots, establishing the strain induced
magneto-electric coupling effects. The CoFe2O4/SrRuO3/PMN-PT nanodots structure
demonstrate multilevel switching of ME coupling coefficient ({\alpha}) by
applying selective positive and negative electric fields in a non-volatile
manner. The retention of two stable states of {\alpha} is illustrated for ~106
seconds, which can be employed to store the digital data in non-volatile memory
devices. Thus the voltage controlled magnetization in the nanodot structures
leads a path towards the invention of energy efficient high-density memory
devices.
