(Invited) Resistive Switching in Mott Insulators: From Fundamentals to Mott Memories

The application of short electrical pulses on narrow gap Mott insulators gives rise to a new phenomenon of resistive switching. This transition is volatile above threshold electric fields of a few kV/cm and stabilizes into a non-volatile RS for higher electric fields. Our works have shown that this phenomenon is driven by the electric field, which triggers an electronic avalanche [1]. This avalanche provokes the collapse of the Mott insulating state at the nanoscale [2] and generates the formation of granular conductive filaments. The resulting non-volatile transition is reversible and these materials have the ability to switch back and forth between two resistance states with possible intermediate levels. This phenomenology was first evidenced on the family of chalcogenide compounds AM 4 Q 8 (A=Ga,Ge; M=V,Nb,Ta,Mo; Q=S,Se), either on single crystals or on thin films [3]. We have recently demonstrated that these properties are actually universal to all canonical Mott insulators such as (V 1-x Cr x ) 2 O 3 or NiS 2-x Se x [4]. In the V 2 O 3 :Cr system, these new results indicate that, beyond temperature for V 2 O 3 and pressure for (V 1-x Cr x ) 2 O 3 , a third tuning parameter, electric field E, is prone to induce an reversible Insulator to Metal transition. This is particularly interesting since these E-induced transitions can occur at room temperature and are hence suitable for applications. Our last results demonstrate that (V 1-x Cr x ) 2 O 3 thin films can be deposited by reactive magnetron co-sputtering [5]. We show that this deposition technique allows controlling the Cr content, oxidation degree and crystallinity after ex-situ annealing. Our last results demonstrate that (V 1-x Cr x ) 2 O 3 thin films can be deposited by reactive magnetron co-sputtering [5]. We show that this deposition technique allows controlling the Cr content, oxidation degree and crystallinity after ex-situ annealing. Our first results on metal-insulator-metal (MIM) devices show that we retrieve the electric-field-induced resistive switching on these TiN/(V 1-x Cr x ) 2 O 3 /TiN symmetric ReRAM cells. The characterization of these Mott memory single cells demonstrate very competitive performances which place narrow gap Mott insulators as promising candidates for ReRAM and memristor applications [6]. [1] V. Guiot et al. , Nat. Commun. 2013 , 4 , 1722 [2] V. Dubost et al. , Nano Lett. 2013 , 13 , 3648 [3] V. Ta Phuoc et al. , Phys. Rev. Lett. 2013 , 110 , 037401 ; A. Camjayi et al. , Phys. Rev. Lett. 2014 , 113 , 086404 ; E. Souchier et al. , Phys. Stat. solidi-RRL 2011 , 5, 53 ; J. Tranchant et al., Thin Solid Films 2013 , 533 , 61 [4] P. Stoliar et al. , Adv. Mater. 2013 , 25 , 3222 ; E. Janod et al., Adv. Funct. Mater. 2015, 25(40) , 6287 [5] M. Querré et al., Thin Solid Films 2015 , doi: 10.1016/j.tsf.2015.12.043 [6] L. Cario et al. – Patent PCT/EP2008/052968 ; M.P. Besland et al. – Patent PCT/EP2010/053442; L. Cario et al. – Patent PCT/EP2013/057500.