Activation energy studies for Fe-II spin crossover molecule [Fe(HB(tz)₃)₂] devices

Magnetic molecules continue to be competitive candidates for spintronic devices and promise ultrafast and low-power devices for data storage and magnetic sensing. Spin crossover molecules undergo a spin-state change in the presence of an external stimulus such as light, temperature, and magnetic field, and this opens a path to nonvolatile memory devices. In particular, [Fe(HB(tz)₃)₂] (tz = 1,2,4-triazol-1-yl) has a transition temperature above room temperature at T_c = 333 K and demonstrates a high cooperativity of 5.7 kJ mol^-1, making it suitable for spintronic device development. The power consumption of such a device directly depends on the activation energy required to change the spin state of the molecule. Previous results show that the measured activation energy of a spin crossover molecule as indicated by the transition temperature can vary with the characterization method. For example, for a similar Fe-II spin crossover molecule, [Fe(H₂B(pz)₂)₂(bipy)] , the measured transition temperature decreased during XAS characterization as compared to magnetometry and transport measurements. Here, we characterize an [Fe(HB(tz)₃)₂] molecular device using temperature dependent Raman spectroscopy, UV-Vis spectroscopy, and transport measurements, and discuss feasibility for spintronic applications.