  The magnetoelectric effects in multiferroics have a great potential in
creating next-generation memory devices. We conceive a new concept of
non-volatile memories based on a type of nonlinear magnetoelectric effects
showing a butterfly-shaped hysteresis loop. The principle is to utilize the
states of the magnetoelectric coefficient, instead of magnetization, electric
polarization or resistance, to store binary information. Our experiments in a
device made of the PMN-PT/Terfenol-D multiferroic heterostructure clearly
demonstrate that the sign of the magnetoelectric coefficient can be repeatedly
switched between positive and negative by applying electric fields, confirming
the feasibility of this principle. This kind of non-volatile memory has
outstanding practical virtues such as simple structure, easy operations in
writing and reading, low power, fast speed, and diverse materials available.
