Нанофізика та фізико-хімічне матеріалознавство

Electrical voltage control of the pressure induced spin transition at room temperature 
Gennadiy Filimonov2, Gennadiy Bukin3, Lyudmila Berezhnaya3, Quanjun Li1,  Georgiy Levchenko1,4
1State Key Laboratory of superhard materials, International Scenter of Future Science of Jilin University; Chine
2Donetsk National University, Donetsk, Ukraine
3Donetsk Institute of Physics and Endeniering named after A.A. Galkin Donetsk, Ukraine
4Donetsk Institute of Physics and Endeniering named after A.A. Galkin NANU of Ukraine, Kyiv, Ukraine.

The progress in IT technologies requires new and new materials and controlling methods of their properties. For decreasing the sizes of memory devices, the exploring of the memory units on molecular scale using spincrossover phenomenon is proposed now. It has to decrease the memory units down to less of nanometer. For that one needs the convenient method of driving and registering the spin transition.  
Fine control and direct monitoring of the spin crossover properties driven by pressure at room temperature are reported for the porous three-dimensional coordination polymer {Fe(pz)[Pt(CN)4]} by using a homemade pressure cell that transforms a DC voltage into pressure. The pressure induced spin state switching is steadily driven through a piezoelectric ceramic element, which transmits the voltage interval 1-4 kV to the pressures in the 0.001-0.035 GPa range. The change of the spin state induced by pressure is easily monitored through changes in the optical spectra of the {Fe(pz)[Pt(CN)4]} compound. After calibrating the spin state change with voltage and pressure variations we have received the sensitive pressure sensor.   The results demonstrate that {Fe(pz)[Pt(CN)4]} responds to as small pressure variations as 0.001 GPa (10 atmospheres), thereby probing its efficacy to work as an effective pressure sensor. 
To the best of our knowledge it is the first time that an electrical voltage is used to induce a spin state switching driven by pressure in a metal coordination compounds This allows us to change the pressure and, therefore, the spin state is not only stepwise, but also smoothly, which is a necessary condition for the practical application of the spin transition phenomenon in memory and other devices. 
In summary, this material also presents the interesting properties, which makes it very attractive in the context of the search for new nanomaterial.