Twist‐Controlled Ferroelectricity and Emergent Multiferroicity in WSe2 Bilayers

• Published in: Advanced materials (Weinheim) 2024-11, Vol.36 (46), p.e2406290-n/a
• Main Authors: Hassan, Yasir, Singh, Budhi, Joe, Minwoong, Son, Byoung‐Min, Ngo, Tien Dat, Jang, Younggeun, Sett, Shaili, Singha, Arup, Biswas, Rabindra, Bhakar, Monika, Watanabe, Kenji, Taniguchi, Takashi, Raghunathan, Varun, Sheet, Goutam, Lee, Zonghoon, Yoo, Won Jong, Srivastava, Pawan Kumar, Lee, Changgu
• Format: Article
• Language: English
• Subjects: Ferroelectric materials; Ferroelectricity; Ferromagnetism; Moire patterns; Moiré superlattices; multiferroic behavior; Room temperature; Selenides; transition metal dichalogenides; Tungsten compounds; twist angle
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202406290

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 (WSe2) 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 WSe2 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. The twisted tungsten diselenide (WSe2) bilayers stacked along with monolayer graphene exhibit 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. Also, 3° twisted WSe2 exhibits ferroelectric and correlation‐driven ferromagnetic ordering, indicating twist‐controlled multiferroic behavior.