Yu Li

Fudan University · Frontier Institute of Chip and System (FICS)

Hafnia-based ferroelectric materials offer a range of advantages, including excellent CMOS compatibility, fast switching speed, and high endurance, positioning them as superior candidates to extend the nonvolatile functionality of static random access memory (SRAM). In this work, we systematically study the working principles of 6T2C nonvolatile SR...

The performance and reliability of ferroelectric thin films at temperatures around a few Kelvin are critical for their application in cryo-electronics. In this work, TiN/Hf 0.5 Zr 0.5 O 2 /TiN capacitors that are free from the wake-up effect are investigated systematically from room temperature (300 K) to cryogenic temperature (30 K). We observe a...

Magnetic skyrmions are nanoscale spin textures whose thermal stability originates from the nontrivial topology in nature. Recently, a plethora of topological spin textures have been theoretically predicted or experimentally observed, enriching the diversity of the skyrmionic family. In this work, we theoretically demonstrate the stabilities of vari...

Oxygen vacancy (V $_{\text {O}}\text {)}$ defects have been proven to significantly influence polarization switching, particularly in hafnia-based ferroelectric (FE) thin films. In this study, we developed a physical model to delve into a fundamentally deeper understanding of various VO dynamics and their impacts on FE responses in Hf $_{{1}-{x}}$...

NbO $_{\textit{x}}$ materials have shown considerable potential for the applications of artificial neurons due to their volatile threshold switching (TS) behavior, fast switching speed, and low power consumption. The TS can be attributed to its negative differential resistance (NDR) effect associated with heat accumulation. Experimental data show...

NbO $_{\textit{x}}$ -based devices exhibit intriguing promise for beyond-CMOS applications due to their dynamic threshold switching (TS) and negative differential resistance (NDR) behaviors. However, an in-depth study on the degradation scheme of such a device is absent. In this work, we investigate the degradation behavior, i.e., the shift of swi...

Tailored magnetic multilayers (MMLs) provide skyrmions with enhanced thermal stability, leading to the possibility of skyrmion-based devices for room-temperature applications. At the same time, the search for additional stable topological spin textures has been under intense research focus. Besides their fundamental importance, such textures may ex...

Magnetic skyrmions are nanoscale spin textures that their thermal stability originates from the nontrivial topology in nature. Recently, a plethora of topological spin textures have been theoretically predicted or experimentally observed, enriching the diversity of the skyrmionic family. In this work, we theoretically demonstrate the stabilities of...

Tailored magnetic multilayers (MMLs) provide skyrmions with enhanced thermal stability, leading to the possibility of skyrmion-based devices for room temperature applications. At the same time, the search for additional stable topological spin textures has been under intense research focus. Besides their fundamental importance, such textures may ex...

The exchange stiffness constant is recognized as one of the fundamental properties of magnetic materials, though its accurate experimental determination remains a particular challenge. In thin films, resonance measurements exploiting perpendicular standing spin waves (PSSWs) are increasingly used to extract this parameter, typically through a deter...

Magnetic skyrmions are nanoscale spin textures that their thermal stability originates from the nontrivial topology in nature. Recently, a plethora of topological spin textures have been theoretically predicted or experimentally observed, enriching the diversity of the skyrmionic family. In this work, we theoretically demonstrate the stabilities of...

Magnetic materials can host a rich variety of nanoscale magnetic structures with non-collinear spin orientations, known as topological spin textures. A plethora of intriguing phenomena entwines magnetism and topology, especially where a Dzyaloshinskii-Moriya interaction is present. Exploitations of the robust topological stability inherent in these...

Magnetic skyrmions have been in the spotlight since their observation in technologically relevant systems at room temperature. More recently, there has been increasing interest in additional quasiparticles that may exist as stable/metastable spin textures in magnets, such as the skyrmionium and the anti-skyrmionite (i.e., a double-antiskyrmion-skyr...

The resistive switching effect in memristors typically stems from the formation and rupture of localized conductive filament paths, and HfO 2 has been accepted as one of the most promising resistive switching materials. However, the dynamic changes in the resistive switching process, including the composition and structure of conductive filaments,...

Magnetic multilayers are promising tunable systems for hosting magnetic skyrmions at/above room temperature. Revealing their intriguing switching mechanisms and associated inherent electrical responses are prerequisites for developing skyrmionic devices. In this Letter, we theoretically demonstrate the annihilation of single skyrmions occurring thr...

Synthetic ferromagnets (SFMs) possess the same layer structure found in the widely studied synthetic antiferromagnets. This consists of two ferromagnetic (FM) layers separated by a nonmagnetic (NM) spacer forming the structure FM1/NM/FM2, but SFMs describe the case where the interlayer exchange coupling promotes the parallel alignment of the magnet...

Magnetic multilayers are promising tuneable systems for hosting magnetic skyrmions at/above room temperature. Revealing their intriguing switching mechanisms and associated inherent electrical responses are prerequisites for developing skyrmionic devices. In this work, we theoretically demonstrate the annihilation of single skyrmions occurring thro...

The topological properties of skyrmionic quasiparticles such as magnetic skyrmions and skyrmioniums enable their applications in future low-power, ultradense nanocomputing and neuromorphic systems. We propose here an all-magnetic skyrmionic interconnect, which has so far been the “missing component.” This interconnect will be of relevance to future...

The interfacing of magnetic materials with nonmagnetic heavy metals with a large spin-orbit coupling, such as Pt, results in an asymmetric exchange interaction at the interface due to the Dzyaloshinskii-Moriya interaction (DMI), which in turn leads to the formation of skyrmions and topological spin structures in perpendicularly magnetized multilaye...

Magnetic skyrmions have attracted considerable interest, especially after their recent experimental demonstration at room temperature in multilayers. The robustness, nanoscale size and non-volatility of skyrmions have triggered a substantial amount of research on skyrmion-based low-power, ultra-dense nanocomputing and neuromorphic systems such as a...

Magnetic skyrmions have attracted considerable interest, especially after their recent experimental demonstration at room temperature in multilayers. The robustness, nanoscale size, and nonvolatility of skyrmions have triggered a substantial amount of research on skyrmion-based low-power, ultradense nanocomputing and neuromorphic systems such as ar...

Skyrmionic textures are being extensively investigated due to the occurrence of novel topological magnetic phenomena, and their promising applications in a new generation of spintronic devices take advantage of the robust topological stability of their spin structures. The development of practical devices relies on a detailed understanding of how s...

In this work, an improved analytical model for the SET switching statistics of HfO2 memristive device is developed from the cell-based percolation model. The statistical results of the SET emergence point related to the beginning stage during SET process are systematically discussed. Moreover, the deviation from Weibull model in high percentiles re...

Magnetic phase transitions are a manifestation of competing interactions whose behavior is critically modified by defects and becomes even more complex when topological constraints are involved. In particular, the investigation of skyrmions and skyrmion lattices offers insight into fundamental processes of topological-charge creation and annihilati...

Magnetic phase transitions are a test bed for exploring the physics of non-equilibrium phenomena in condensed matter, which become even more complex when topological constraints are involved. In particular, the investigation of skyrmions and skyrmion lattices offers insight into fundamental processes of topological-charge creation and annihilation...

In article number 1604306, Shibing Long, Ming Liu and co-workers, review performance improvements in resistive switching devices. The main focus is on filamentary switching behavior, in the aspects of materials modulation, device structure design and switching operation scheme optimization. In particular, 2D nanomaterials that play active roles and...

In resistive random access memories, modeling conductive filament growing dynamics is important to understand the switching mechanism and variability. In this paper, a universal Monte Carlo simulator is developed based on a cell switching model and a tunneling-based transport model. Driven by external electric field, the growing process of the nano...

Reversible chemical and structural changes induced by ionic motion and reaction in response to electrical stimuli leads to resistive switching effects in metal-insulator-metal structures. Filamentary switching based on the formation and rupture of nanoscale conductive filament has been applied in non-volatile memory and volatile selector devices wi...

In this letter, the experimental reset voltage and current statistics in a Cu/HfO2/Pt RRAM device are found to deviate from the Weibull model in the high percentiles. A clusteringmodel is developed for the reset statistics based on the cell-based model. The relationship between the parameters (Weibull slope, scale factor, and clustering factor) of...