Can we construct a molecular multiferroic electronic device?*

As the expectations for novel printable electronics grow, the design of flexible and high-density nonvolatile molecular memory devices remains a hot topic. Voltage control of "molecular spintronics" (where charge and spin both matter) is a major goal because such nonvolatile molecular structures have the very real possibility of providing a room temperature nonvolatile device on a length scale less than 10 nm (semiconductor industry goals) while delivering low power GHz nonvolatile local logic or memory operations. The successes in addressing the grand challenge of manipulating magnetically ordered states by electrical approach suggest new routes to developing novel spintronics.

While much is in its infancy, molecular spintronics has now been shown to be possible. The spin crossover (SCO) phenomenon, in 3d transition metal compounds, through the manipulation of interfacial chemistry, can be exploited to create voltage-controlled isothermal changes in the electronic structure. This has been shown for the Fe (II) spin crossover complexes interfaced with molecular ferroelectrics. This nonvolatile isothermal voltage-controlled switching, at room temperature, is evident in both spectroscopy and transport studies of thin film bilayer devices [1,2]. This comes at a lower energy cost,  faster speeds, and far less fabrication complexity than the currently commercially available nonvolatile memory based on magnetic tunnel junctions. If the molecular system(s) can be made into ink, then printable electronics are a very real possibility. Even better, the fact that molecular device fabrication is possible at room temperature from solution, means that three-dimensional memory arrays are possible - if the power dissipation is small.

But there are challenges still to be addressed. The key problem of the high impedance of the device has now been addressed through chemistry. The key take-away point is that molecular nonvolatile room temperature "memory" devices have been realized and new developments in chemistry should lead to better molecular nonvolatile electronic devices.