Nonvolatile Transtance Change Random Access Memory Based On Organic Magnetoelectric Heterostructures

With the high-speed development of information,a universal nonvolatile randomaccess memory has aroused much attention in information and materials.Transtance change random-access memory(TCRAM)is a new type of nonvolatile memory based on the nonlinear magnetoelectric(ME)coupling effects of multiferroics.It is mainly made of multiferroic heterostructures of ferroelectric and magnetic materials,using different ME coefficients to encode information.Positive and negative ME coefficients can be act as two distinctive states to encode binary information as “0” and “1”.Polarization of ferroelectric materials can be tuned to write information by applying electric-field pulses to the ferroelectric materials;the ME coefficients of multiferroic heterostructures can be read to read out information.Its structure is very simple,writing operation is energy efficient and reading operation is nondestructive.The device made of soft films have exhibited great promise for application in wearable area.The experiments were done on the soft organic TCRAM based on P(VDF-Tr FE)films in this work.The organic ME heterostructures P(VDF-TrFE)/Metglas were prepared by the solgel technique.A series of ME measurements were done on P(VDF-TrFE)/Metglas heterostructures.The ME voltage coefficients of the heterostructures can be switched reproducibly between different two levels by applying selective electric-field pulses at fixed in-plane dc bias magnetic field(Hdc).Furthermore,the ME voltage coefficients of the heterostructures can be switched reproducibly among different four levels by applying selective electric-field pulses at fixed Hdc.The results demonstrate the feasibility of P(VDF-TrFE)/Metglas organic ME heterostructures in multilevel TCRAM.To demonstrate the feasibility of multilevel TCRAM at in-plane zero Hdc,we prepared organic ME heterostructures P(VDF-TrFE)/Ni due to larger remanence and its magnetostriction.The ME voltage coefficients of the heterostructures can be switched reproducibly between different two levels and among four and eight levels at zero in-plane Hdc.The feasibility of multilevel TCRAM at in-plane zero Hdc was demonstrated by applying selective electric-field pulses.It simplifies the reading operation and reduces energy consumption.