Widely Tunable Berry Curvature in the Magnetic Semimetal Cr _{1+ δ} Te ₂

Journal Article · 11 February 2023 · Advanced Materials

DOI: https://doi.org/10.1002/adma.202207121 · OSTI ID:1924139

Fujisawa, Yuita ^[1]; Pardo‐Almanza, Markel ^[1]; Hsu, Chia‐Hsiu ^[2]; Mohamed, Atwa ^[1]; Yamagami, Kohei ^[1]; Krishnadas, Anjana ^[1]; Chang, Guoqing ^[3]; Chuang, Feng‐Chuan ^[4]; Khoo, Khoong Hong ^[5]; Zang, Jiadong ^[6]; Soumyanarayanan, Anjan ^[7]; Okada, Yoshinori  ^[1]

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1. Quantum Materials Science Unit Okinawa Institute of Science and Technology (OIST) Okinawa 904‐0495 Japan
2. Quantum Materials Science Unit Okinawa Institute of Science and Technology (OIST) Okinawa 904‐0495 Japan, Department of Physics National Sun Yat‐sen University Kaohsiung 80424 Taiwan, Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan, Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
3. Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
4. Department of Physics National Sun Yat‐sen University Kaohsiung 80424 Taiwan, Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan, Center for Theoretical and Computational Physics National Sun Yat‐sen University Kaohsiung 80424 Taiwan
5. Institute of High Performance Computing Agency for Science Technology and Research Singapore 138632 Singapore
6. Department of Physics and Astronomy University of New Hampshire Durham NH 03824 USA, Materials Science Program University of New Hampshire Durham NH 03824 USA
7. Department of Physics National University of Singapore Singapore 117551 Singapore, Institute of Materials Research and Engineering Agency for Science Technology and Research Singapore 138634 Singapore

Abstract Magnetic semimetals have increasingly emerged as lucrative platforms hosting spin‐based topological phenomena in real and momentum spaces. Cr _{1+ δ} Te ₂ is a self‐intercalated magnetic transition metal dichalcogenide (TMD), which exhibits topological magnetism and tunable electron filling. While recent studies have explored real‐space Berry curvature effects, similar considerations of momentum‐space Berry curvature are lacking. Here, the electronic structure and transport properties of epitaxial Cr _{1+ δ} Te ₂ thin films are systematically investigated over a range of doping, δ (0.33 – 0.71). Spectroscopic experiments reveal the presence of a characteristic semi‐metallic band region, which shows a rigid like energy shift with δ. Transport experiments show that the intrinsic component of the anomalous Hall effect (AHE) is sizable and undergoes a sign flip across δ. Finally, density functional theory calculations establish a link between the doping evolution of the band structure and AHE: the AHE sign flip is shown to emerge from the sign change of the Berry curvature, as the semi‐metallic band region crosses the Fermi energy. These findings underscore the increasing relevance of momentum‐space Berry curvature in magnetic TMDs and provide a unique platform for intertwining topological physics in real and momentum spaces.

• Research Organization: Univ. of New Hampshire, Durham, NH (United States)
• Sponsoring Organization: National Center for Theoretical Sciences and the Ministry of Science and Technology of Taiwan; SpOT-LITE program; USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: SC0020221
• OSTI ID: 1924139
• Journal Information: Advanced Materials, Journal Name: Advanced Materials Journal Issue: 12 Vol. 35; ISSN 0935-9648
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: Germany
• Language: English