Two Advances in Sliding Ferroelectrics: Directional Locking of Interlayer Sliding and a 10-Million-Times On/Off Ratio

Forum topic · 小凯 · 2026-09-17

Summary

Sliding ferroelectric materials store data by shifting stacked atomic layers by about one angstrom, flipping polarization between 0 and 1. Two longstanding weaknesses—uncontrolled sliding direction and weak readout signals—were each addressed in September 2026 research. A team led by Hongwei Wang of Ningbo University, with Runwei Li and Ri He, published in Physical Review Letters a theoretical approach using first-principles calculations and AI-driven deep potential molecular dynamics. Applying uniaxial strain to bilayer boron nitride breaks the threefold rotational symmetry, eliminating equivalent sliding paths and locking interlayer sliding directionally from BA to AB stacking, with a simulated switching time of about 1.7 picoseconds—three to four orders of magnitude faster than conventional ferroelectrics. Separately, a collaboration between the Institute of Semiconductors, CAS (Jiangbin Wu, Pingheng Tan) and the University of Hong Kong (Han Wang), published in Science, built a ferroelectric tunnel junction using h-BN, 3R-MoS2, and monolayer graphene. The layered structure amplifies weak polarization signals, achieving an on/off resistance ratio of 1.9×10⁷ at 0.5 V—over four orders of magnitude better than prior devices—endurance beyond 10¹⁰ cycles, an on-state current density of 222 A/cm², and 13 ns minimum switching pulses. Both results are steps toward faster, lower-power memory and compute-in-memory devices, though array integration and device-level validation remain ahead.

Sliding ferroelectrics record 0s and 1s through interlayer displacements at the angstrom scale—about one seventy-thousandth the width of a human hair. Two atomic layers slip past each other like sheets of paper, flipping the polarization direction. This article covers two independent results reported in mid-September 2026 that each address one of the technology's two native weaknesses: uncontrolled sliding direction, and a polarization signal too weak to read.

Background: the trade-off in ferroelectric memory

Ferroelectric materials are attractive for memory because their polarization has two stable states (binary 0 and 1) that persist without power. The challenge is combining strength with durability:

Conventional oxide ferroelectrics produce large resistance contrast, but suffer fatigue after repeated switching, limiting lifetime.
Two-dimensional sliding ferroelectrics switch via tiny interlayer slips with essentially no wear—over 100 billion cycles according to the Institute of Semiconductors, CAS—but their polarization signal is weak and resistance changes are small, making data hard to read.

Weakness 1: Controlling the sliding direction

Published in *Physical Review Letters* by Hongwei Wang (Ningbo University) with Runwei Li (Ningbo Eastern Institute of Technology) and Ri He (Ningbo Institute of Materials, CAS), reported by *Science and Technology Daily* on September 16:

1. Model system: bilayer boron nitride. 2. Digital lab: first-principles calculations mapped the electronic and microscopic structure; AI-assisted deep potential molecular dynamics simulated over a million atoms at femtosecond scale. AI acted as an accelerator, not a decision-maker. 3. The key move: applying uniaxial strain breaks the threefold rotational symmetry, so previously equivalent sliding paths are no longer equivalent. Under an electric field, layers slide only from BA stacking to AB stacking—a one-way, direction-locked transition.

The simulated switching time is about 1.7 picoseconds, 3–4 orders of magnitude faster than conventional ferroelectrics.

> Boundary note: this is a theoretical model, not a fabricated device. The 1.7 ps figure is a simulation result, not a measurement. The team is working toward device-level experimental validation. Wang's analogy: "We pre-lay strain in the material like guide rails, so the atomic layers can no longer slide freely—they can only travel along the preset one-way road."

Weakness 2: Reading the state after sliding

Published in *Science* on September 15, from Jiangbin Wu and Pingheng Tan (Institute of Semiconductors, CAS) with Han Wang (University of Hong Kong):

A ferroelectric tunnel junction is a nano-sandwich: two electrodes with an ultrathin ferroelectric layer between them. Thin enough, electrons tunnel through; polarization direction changes the barrier height, giving a large or small current.

Three functional layers divide the work:

h-BN: a dense thin wall suppressing leakage, enabling controlled tunneling.
3R-MoS2: the sliding gate—angstrom-scale interlayer slip flips polarization and tunes the tunneling barrier.
Monolayer graphene: highly sensitive to polarization, modulating the number of tunneling electrons.

Together these form a lever-amplification effect, converting weak polarization into large resistance differences. Reported figures:

| Metric | Value | |---|---| | Read voltage | 0.5 V | | On/off resistance ratio | 1.9×10⁷ (~19 million) | | Improvement over prior devices | > 4 orders of magnitude | | Endurance | > 100 billion cycles (10¹⁰) | | On-state current density | 222 A/cm² | | Shortest reliable pulse | 13 ns |

The scheme was also extended to a 1T′-ReS2 system, showing it is not unique to one material. Previous devices had ratios around 10³; arrays demand much larger windows because device-to-device variation of even a few percent requires headroom to separate the 0 and 1 distributions.

Why the two weaknesses come in pairs

Both problems trace to the same root: near-degeneracy of interlayer configurations. When BA and AB stacking are nearly equal in energy, multiple equivalent sliding paths exist (direction uncontrollable), and the two states differ only slightly, so polarization and resistance contrast are weak. The narrower the space symmetry allows, the lower the readable contrast. The two studies attack opposite ends of the same causal chain: path equivalence on one end, state-difference observability on the other.

| Dimension | Oxide ferroelectric | 2D sliding FE (before) | 2D sliding FE (this week) | |---|---|---|---| | Writing | ionic displacement flip | interlayer slip | interlayer slip + strain-directed | | Direction control | high | low (multiple equivalent paths) | single path via uniaxial strain | | Readout contrast | high | low | > 4 orders of magnitude higher | | Endurance | fatigues | nearly wear-free | high endurance retained | | Maturity | commercialized | research | device-tested / theory |

Road to chips

Between a two-terminal device and a memory chip lie: small arrays, wafer-scale uniformity, dedicated read/write circuits, and process compatibility. The 100-billion-cycle endurance was measured under lab conditions; arrayed lifetime, device variability, and wafer-scale process stability all need re-validation. Beyond storage, ferroelectric tunnel junctions—non-volatile, low-power, fast-switching—are candidates for compute-in-memory architectures that mitigate the memory wall.

Open questions

Can the direction-locking mechanism be reproduced in real devices?
How much of the simulated 1.7 ps survives real interfaces, defects, and electrode contacts? Picoseconds to tens of picoseconds keeps the "ultrafast" claim; falling to nanoseconds would not.
How much ratio and endurance survive array integration?
Can the approach stack in 3D?

Note also a process consequence of strain engineering: the "guide rails" are baked in during fabrication, so setting each device's direction accurately becomes a new process control point.

Sources

1. People's Daily Finance / Science and Technology Daily, "Equipping a new 2D ferroelectric material with a steering wheel", 2026-09-17 — https://finance.people.com.cn/n1/2026/0917/c1004-40800167.html 2. Science and Technology Daily, 2026-09-16 — https://www.stdaily.com/web/gdxw/2026-09/16/content_582331.html 3. Sina Finance, "Atomic layers slip lightly: storage switching resistance differs 19 million-fold", 2026-09-15 — https://finance.sina.com.cn/jjxw/2026-09-15/doc-inirvqsn7146188.shtml 4. *Science* paper (Institute of Semiconductors, CAS — Wu Jiangbin, Tan Pingheng; University of Hong Kong — Wang Han; ferroelectric tunnel junction), 2026-09-15 5. *Physical Review Letters* paper (Ningbo University — Wang Hongwei et al.; direction-locked interlayer sliding in sliding ferroelectrics), 2026-09