Twist‐Controlled Ferroelectricity and Emergent Multiferroicity in WSe<sub>2</sub> Bilayers
Yasir Hassan, Budhi Singh, Minwoong Joe, Byoung‐Min Son, Tien Dat Ngo, Younggeun Jang, Shaili Sett, Arup Singha, Rabindra Biswas, Monika Bhakar, Kenji Watanabe, Takashi Taniguchi, Varun Raghunathan, Goutam Sheet, Zonghoon Lee, Won Jong Yoo, Pawan Kumar Srivastava, Changgu Lee
Abstract
Abstract Recently, researchers have been investigating artificial ferroelectricity, which arises when inversion symmetry is broken in certain R‐stacked, i.e., zero‐degree twisted, van der Waals (vdW) bilayers. Here, the study reports the twist‐controlled ferroelectricity in tungsten diselenide (WSe 2 ) bilayers. The findings show noticeable room temperature ferroelectricity that decreases with twist angle within the range 0° < θ < 3°, and disappears completely for θ ≥ 4°. This variation aligns with moiré length scale‐controlled ferroelectric dynamics (0° < θ < 3°), while loss beyond 4° may relate to twist‐controlled commensurate to non‐commensurate transitions. This twist‐controlled ferroelectricity serves as a spectroscopic tool for detecting transitions between commensurate and incommensurate moiré patterns. At 5.5 K, 3° twisted WSe 2 exhibits ferroelectric and correlation‐driven ferromagnetic ordering, indicating twist‐controlled multiferroic behavior. The study offers insights into twist‐controlled coexisting ferro‐ordering and serves as valuable spectroscopic tools.