Multiferroic Ti$_3$C$_2$T$_x$ MXene with Tunable Ferroelectric-controlled High Performance Resistive Memory Devices

Multiferroic (MF) devices based on simultaneous ferroelectric and ferromagnetic phenomena are considered to be promising candidates for future bi-functional micro/nano-electronics. The multiferroic phenomena in two-dimensional materials is rarely reported in literature. We reported a simple approach to reveal frequency-dependent ferroelectricity and mutiferroicity in Ti$_3$C$_2$T$_x$ MXene film at room-temperature. To study the frequency and poling effect on ferroelectricity as well as multiferroicity, we performed electric polarization vs. electric field measurement at different external frequencies measured under zero and non-zero static magnetic fields. In order to further investigate this effect, the magneto-electric (ME) coupling was also performed to confirm the multiferroic nature of our synthesized Ti$_3$C$_2$T$_x$ MXene film. The ferroelectric hysteresis effect was attributed to the switching of electric domain walls under low frequencies that continue to respond to at much extent to the higher frequencies. The coupling between disordered electric dipoles with local spin moments could cause presence of strong magneto-electric coupling. Moreover, the bipolar resistive switching in trilayer memory devices also supports the ferroelectric behavior of HT- Ti$_3$C$_2$T$_x$ MXene film and showed uniform repeatability in switching behavior due to minimum dielectric loss inside ferroelectric HT-Ti$_3$C$_2$T$_x$ MXene along with improved on/off ratio in comparison to non-ferroelectric Ti$_3$C$_2$T$_x$ MXene. The unique multiferroic behavior along with ferroelectric-tuned memristor devices reported here at room temperature will help understand the intrinsic nature of 2D materials and will establish novel data storage devices.