Information units are progressively approaching the fundamental physical limits of the integration density, including in terms of extremely small sizes, multistates and probabilistic traversal. However, simultaneously encompassing all of these characteristics in a unit remains elusive. Here, via real-time in situ electrical monitoring, we clearly observed stochastic alterations of multiple conductance states in Sc2C2@C88. The true random bit sequence generated exhibited an autocorrelation function whose confidence interval fell within ±0.02, demonstrating high-quality randomness. The alterations of multiple conductance states are controllable, that is, whose probability distributions could traverse from “0” to “1”, enabling us to factorize 551 into its prime factors. Furthermore, we proposed a matrix-chain multiplication scheme and experimentally verified the multiplication of two 4 × 4 state-transition matrices with a small maximum error < 0.05. Combined with theoretical calculations, the stochastic but controllable multistates are probably attributed to the rich energy landscape, which could be stepwise changed by the electric field. Our findings reveal extremely small multi-level probabilistic bit for matrix multiplication, which pave the way for ultracompact intelligent electronic devices.
Xiangqi Wang†, Cong Wang†, Yupeng Wang†, Chunhui Ye, Azizur Rahman, Min Zhang, Suhan Son, Jun Tan*, Zengming Zhang*, Wei Ji*, Je-Geun Park6,7,8, and Kai-Xuan Zhang†*
Abstract:
Van der Waals (vdW) magnets, with their two-dimensional (2D) atomic structures, provide a unique platform for exploring magnetism at the nanoscale. Although there have been numerous reports on their diverse quantum properties, the emergent interfacial magnetism— artificially created at the interface between two layered magnets—remains largely unexplored. This work presents observations of such emergent interfacial magnetism at the ferromagnet/antiferromagnet interface in a vdW heterostructure. We report the discovery of an intermediate Hall resistance plateau in the anomalous Hall loop, indicative of emergent interfacial antiferromagnetism fostered by the heterointerface. This plateau can be stabilized and further manipulated under varying pressures but collapses under high pressures over 10 GPa. Our theoretical calculations reveal that charge transfer at the interface is pivotal in establishing the interlayer antiferromagnetic spin-exchange interaction. This work illuminates the previously unexplored emergent interfacial magnetism at a vdW interface comprised of a ferromagnetic metal and an antiferromagnetic insulator, and highlights its gradual evolution under increasing pressure. These findings enrich the portfolio of emergent interfacial magnetism and pave the way for future investigations on vdW magnetic interfaces and the development of next-generation spintronic devices.
Two-dimensional room-temperature ferromagnet CrTe2 is a promising candidate material for spintronic applications. However, its large-scale and cost-effective synthesis remains a challenge. Here, we report the fine controllable synthesis of wafer-scale 1T-CrTe2 films on a SiO2/Si substrate using plasma-enhanced chemical vapor deposition at temperatures below 400 ºC. Magnetic hysteresis measurements reveal that the synthesized 1T-CrTe2 films exhibit perpendicular magnetic anisotropy along with distinct step-like magnetic transitions. We find that 1T-CrTe2 is susceptible to oxygen adsorption even in ambient conditions. Our theoretical calculations indicate that the oxidation of surface layers is crucial for the absence of out-of-plane easy axis in few-layer CrTe2, while the interlayer antiferromagnetic coupling among the upper surface layers leads to the observed step-like magnetic transitions. Our study provides a Si-CMOS compatible approach for the fabrication of magnetic two-dimensional materials and highlights how unintentional adsorbents or dopants can significantly influence the magnetic behaviors of these materials.
Two-dimensional Janus materials exhibit unique physical properties due to broken inversional symmetries. However, it remains elusive to synthesize Janus monolayer crystals with tailored long-range magnetic orders. Here, we show a 2 ×√𝟑 charge density wave (CDW) transition and regulations of magnetization in a uniform Janus CrTeSe monolayer, selectively selenized from a pristine CrTe2 monolayer using molecular beam epitaxy. Scanning transmission electron microscopy images indicate the high quality and uniformity of the Janus structure. Spin-polarized scanning tunneling microscopy/spectroscopy measurements and density functional theory calculations unveil a robust zigzag antiferromagnetic order and the CDW transition in the CrTeSe monolayer. The one-side selenization breaks the vertical inversion symmetry, rotating the magnetic moment directions to the in-plane direction. The CDW transition opens a gap at the Fermi level and reorients the magnetic moments in tilted directions. Our work demonstrates the construction of large-area Janus structures and the tailoring of electronic and magnetic properties of two-dimensional Janus layers.
Miniaturizing van der Waals (vdW) ferroelectric materials to atomic scales is essential for modern devices like nonvolatile memory and sensors. To unlock their full potential, their growth mechanisms, interface effects, and stabilization are preferably investigated, particularly for ultrathin 2D nanosheets with single-unit cell thickness. This study focuses on Bi2TeO5 (BTO) and utilizes precise control over growth kinetics at the nucleation temperature to create specific interfacial reconfiguration layers. Ultrathin BTO nanosheets with planar ferroelectricity at a single-unit cell thickness are successfully grown. Atomic-scale characterization reveals a disordered distribution of elements in the interfacial layer, which buffers strain from lattice mismatch. The theoretical calculations support these observations. Furthermore, this strategy also can be extended to the growth of a variety of 2D ternary oxide nanosheets. This work contributes to a better understanding of growth and stability mechanisms in 2D ultrathin nanosheets.
