Evolution Of Ni Nano?laments And Electromagnetic Coupling In The Resistive Switching Of NiO

In recent years, resistive switching（RS） effect has attracted considerable attention due to its scientific interest and applications in resistive random access memory（RRAM） and novel computer logic architectures. It is well known that the progress of charge-based memories, such as the dynamic random access memory and Flash memory, is hindered by the fundamental scaling limit. Therefore non-charge-based memory with low cost, low power dissipation, high speed and high-density integration has been in urgent need. In this regard, RRAM which combines the advantages is generally recognized as one of the most competitive candidates for the next-generation non-volatile memory. So far, a number of mechanisms have been proposed to decipher RS effect. The mechanism is still an open question although the formation/rupture of conducting nanofilament has been argued to be the promising one. It is generally believed that the RS effect in NiO results from the formation/ rupture of Ni nanofilament. Up to now, there is not a whole nanofilament throughout the NiO film in the LRS from the top electrode（TE） to the bottom electrode（BE） with structure analysis. However, it is not clear whether a single nanofilament or multiple nanofilaments are involved in the LRS and HRS, and how the nanofilament or nanofilaments evolve in the RESET process. Since Ni nanofilaments should be ferromagnetic, how about the electromagnetic coupling? Aim at these problems above, this thesis has researched the RS effect in NiO thin film, and the main work can be divided to three parts as follows:Firstly, Ni O thin ?lms were grown on Pt/Ti/Si O₂/Si substrates by pulsed laser deposition. We exhibits a whole Ni nanofilament throughout the Ni O film from the TE to the BE with structure analysis by the transmission electron microscopy（TEM） for the first time.Secondly, we found that multi-nanofilaments are involved by impedance characteristics and R-T curves of the LRS and HRS with different resistances. The relation between the rupture gap of the nanofilaments and the resistance of HRS is fitted, which shows the evolution of nanofilaments: They become thin and rupture separately in the RESET process with subsequent increase of the rupture gaps.Thirdly, electromagnetic coupling. We introduce the tuning of the magnetism of the devices electrically. The difference of saturation magnetization of LRS and HRS reaches 14%. It’s very obvious.What’s more, we give the reverse tuning. It shows the AMR effect in LRS and anomalous AMR, AMR and TMR effect in HRS. In RS effect of Ni O, we demonstrate electromagnetic coupling, which opens a new avenue for multifunctional devices.