The significant role of interfaces in potential low energy nonvolatile voltage controlled multiferroic spintronic transistors*

Here the influence of heteromolecular interfaces will be compared with interfaces with a magnetoelectric oxide and in each case the local magnetic moment plays a significant role. These interface effects matters because the control of interface interactions is essential to two very different approaches to a competitive multiferroic voltage controlled nonvolatile spintronic transistor with a delay time less than CMOS and an energy cost much less than CMOS. Molecular spintronic transistors have now been shown to be possible without  ferromagnetism. The spin crossover (SCO) phenomenon, specifically the spin state in 3d transition metal compounds, can be exploited to create voltage-controlled isothermal changes in the electronic structure and conductance, through the manipulation of an organic ferroelectric interface. This nonvolatile isothermal voltage-controlled spin state switching, at room temperature, is evident in both spectroscopy and transport studies of thin film bilayer devices [1,2]. The role of the interface is not only crucial, but the influence of the interface extends far beyond just those spin crossover molecules in intimate contact with the organic ferroelectric. Interfaces also play a role in the spintronic transistor based on antiferromagnetic magnetoelectric oxides and possible 2D semiconductor channels. Through detailed studies of the electronic band structure, the pertinent interfaces, more is understood about the influence of the voltage-controlled boundary polarization of the magneto-electric oxide Cr₂O₃(001) on a 2D semiconductor channel or metal with large Stoner susceptibility. The existing working voltage controlled nonvolatile oxide magneto-electric spintronic transistors, the influence of the boundary spin polarization does not extend very far from the interface except in special cases (Pd on Cr₂O₃(001)), which will be discussed. Like the molecular spin crossover heterostructures, no applied external magnetic field is required [3].

[1] G. Hao, et al., Appl. Phys. Lett. 114 (2019)032901, [2] A. Mosey, et al. J. Physical Chemistry Letters 11 (2020)8231−8237, [3] A Mahmood, et al., Nature Comm. 12 (2021)1674