Concerted Carrier-Barrier Dynamics in van der Waals Schottky Junctions Revealed by Time-Resolved Atomic Force Microscopy

Munenori Yokota; Hiroyuki Mogi; Yutaka Mera; Katsuya Iwaya; Taketoshi Minato; Shoji Yoshida; Osamu Takeuchi; Tatsuo Nakagawa; Hidemi Shigekawa

arXiv · 2602.21463

Concerted Carrier-Barrier Dynamics in van der Waals Schottky Junctions Revealed by Time-Resolved Atomic Force Microscopy

Munenori Yokota·Hiroyuki Mogi·Yutaka Mera·Katsuya Iwaya·Taketoshi Minato·Shoji Yoshida·Osamu Takeuchi·Tatsuo Nakagawa·Hidemi Shigekawa

View original source ↗Read source document ↗Export metadata ↓

Abstract

Schottky junctions based on transition-metal dichalcogenides (TMDCs) have emerged as key building blocks for next-generation optoelectronic devices that demand ultrafast response and high sensitivity. However, the ultrafast, nanoscale carrier dynamics at these interfaces, crucial for device performance, have remained experimentally elusive. Here, we introduce optical pump-probe time-resolved atomic force microscopy to directly visualize, in real space, the nanosecond-scale modulation of the Schottky barrier potential at a van der Waals junction formed by point contact between WSe2 and a PtIr tip. Complementary analyses using transient absorption spectroscopy and light-modulated current-voltage characteristics together with model simulations reveal that time-resolved currents originate from the concerted temporal evolution of photoexcited carriers and the subsequent barrier response, processes that also define the rate-limiting steps of the photocurrent. Our results uncover the essential interfacial dynamics that underpin TMDC-based photodetectors and photovoltaic elements, while establishing a new measurement paradigm that complements and extends existing spectroscopic techniques. This approach provides direct access to nonequilibrium processes hidden at nanoscale interfaces, offering a powerful route to rational design of high-performance optoelectronic devices.

Explore related subjects

cond-mat.mes-hall cond-mat.mtrl-sci

Keep this discovery

BibTeX RIS

Munenori Yokota, Hiroyuki Mogi, Yutaka Mera, Katsuya Iwaya, Taketoshi Minato, Shoji Yoshida, Osamu Takeuchi, Tatsuo Nakagawa, Hidemi Shigekawa. 2026-02-25. Concerted Carrier-Barrier Dynamics in van der Waals Schottky Junctions Revealed by Time-Resolved Atomic Force Microscopy. https://arxiv.org/abs/2602.21463

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Emergence of spin-orbit coupling among spin, atomic orbital, and Bloch dynamics in Janus double-transition-metal MXenes

We found a spin-orbit coupling to cause a simultaneous correlation among three degrees of freedom, the electronic spin, orbital, and Bloch dynamics in an investigation into the electronic structure of Janus double-transition-metal MXenes, Mo$_2$HfC$_2$OS and W$_2$HfC$_2$OS. In this paper, it is also revealed that the spin-orbit coupling causes a staggered spin configuration with a trigonal pattern around the $\Gamma$ point near the insulating gap. We developed a reduced Hamiltonian describing the electronic states and show that the spin-orbit coupling cannot be equated with conventional forms for a single electron in solids, LS, Rashba, and Dresselhaus couplings, even in the approximation under the low-energy and small wave number condition. Because of the intrinsic shape of the conduction band, a trigonally alternating spin-momentum locking emerges with the spin axis perpendicular to the layer plane. The theoretical analysis shows that these Janus materials can provide a platform for exploring the spin-related phenomena due to the trigonal spin-momentum locking other than Rashba and Dresselhaus types.

cond-mat.mes-hall↗

arXiv2026

A substrate booster for P-type 2D ferromagnetic semiconductor

Spin transistors with its both charge and spin properties tuned via electrostatic gating are believed capable for widespread use, which however have proven challenging due to the extreme rareness of their physical base -- magnetic semiconductors. The latter are limited within very few systems including diluted magnetic semiconductors (DMS) and two-dimensional ferromagnetic semiconductors (2D-FMS), and known to suffer from inadequate gate-tunability of their electric and/or magnetic properties. Here, we show a substrate engineering paradigm by interfacing few-layered Cr$_{2}$Ge$_{2}$Te$_{6}$ (FL-CGT) with an antiferromagnetic insulator CrOCl. Owing to the subtle interfacial charge transfer couplings, CGT can be drastically turned from an ambipolar semiconductor into a high performance P-type semiconductor. When cooled below the Curie temperature, the ON-OFF ratio in such substrate-boosted FMS field-effect transistor (FET) reaches 10$^{5}$ with its coercive field $H_{c}$ of magnetic hysteresis loop tunable by a factor of more than 200$\%$, enabling {gate-assisted magnetic switching in the prototype semiconducting spin transistor architecture}. A crossover from critical power-law scaling to a dual power-law behaviour under heavy hole doping was further observed. Our findings {signify} an efficient interfacial charge transfer and electrically modulated magnetic anisotropy energy supported by calculations. This high performance P-type FMS-FET system suggests that active substrate-boosting paradigm might be a powerful path for the investigation of future gate-tunable spintronic devices.

cond-mat.mes-hall↗

arXiv2026

In-plane magnetic field control of anomalous Hall response enabled by magnetic anisotropy engineering

Engineering magnetic anisotropy provides a powerful route to control magnetization orientation and unlock emerging functionalities in opto-spintronic and current-driven devices. Beyond its role in magnetization reversal, the effective anisotropy can strongly influence the magnetotransport response, offering an additional degree of freedom to tune new device functionalities. In this work, we report a magnetotransport study of a ferrimagnetic [Tb/Co]$_{\times 5}$ multilayer grown with a Tb thickness gradient, whose wedge-shaped tilts the uniaxial anisotropy axis slightly away from the film normal. Anomalous Hall resistivity measurements from 80 K to 300 K reveal a spin reorientation transition, while the angular dependence of the magnetotransport responses exposes the crucial role of the tilted anisotropy. A simplified macrospin model reproduces the full angular response across the transition and shows that the observed anomalous Hall effect when the in-plane magnetic field is applied originates from the tilt of the uniaxial anisotropy axis, which supplies a built-in symmetry-breaking mechanism, enabling in-plane field control over the out-of-plane anomalous Hall response, sign included. These findings establish tilted magnetic anisotropy as a promising route toward Hall effect-based sensor applications and highlight Tb/Co multilayers as a versatile platform for anisotropy-engineered spintronic devices.

cond-mat.mes-hall↗