Multifilamentary Character of Anticorrelated Capacitive and Resistive Switching in Memristive Structures Based on (Co-Fe-B)x(LiNbO3)100-x Nanocomposite

Resistive and capacitive switching in capacitor metal/nanocomposite/metal (M/NC/M) struc- tures based on (Co-Fe-B)(x)(LiNbO3)(100-x) NC fabricated by ion-beam sputtering with metal content x approximate to 8-20 at. % is studied. The peculiarity of the structure synthesis was the use of increased oxygen content (approximately equal to 2 x 10(-5) Torr) at the initial stage of the NC growth. The NC films, along with metal nanogranules of 3-6 nm in size, contained a large number of dispersed Co (Fe) atoms (up to approximately 10(22) cm(-3)). Measurements are performed both in dc and ac (frequency range 5-13 MHz) regimes. When switching structures from high-resistance (R-off) to low-resistance (R-on) state, the effect of a strong increase in their capacity is found, which reaches 8 times at x approximate to 15 at. % and the resistance ratio R-off:R-on approximate to 40. The effect is explained by the synergetic combination of the multifilamentary character of resistive switching (RS) and structural features of the samples associated, in particular, with the formation of a high-resistance and strongly polarizable LiNbO3 layer near the bottom electrode of the structures. The proposed model is confirmed by investigations of RS of two-layer nanoscale M/NC/LiNbO3/M structures as well as by studies of the magnetization of M/NC/M structures in the pristine state and after RS.