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TT: Fachverband Tiefe Temperaturen
TT 45: 2D Materials: Electronic Structure and Exitations III (joint session O/HL/TT)
TT 45.4: Vortrag
Donnerstag, 20. März 2025, 11:15–11:30, H11
magnetic-field-induced dimensionality transition of charge density waves in strained 2H-NbSe2 — •Ryo Ichikawa1, Yukiko Takahashi2, Eiichi Inami3, and Toyo Kazu Yamada1, 4 — 1Department of Material Science, Chiba University — 2National Institute for Material Science, Tsukuba — 3School of system Engineering, Kochi University of Technology — 4Molecular Chirality Research center, Chiba University
Layered transition metal dichalcogenides (TMDs) exhibit various correlated phases, including charge density waves (CDW), superconductivity, and magnetic orders. Bulk 2H-NbSe2 (2H niobium diselenide) is one of the most extensively studied TMDs, showing a triangular (3Q) incommensurate CDW with a 3a period in real space (3 * 3, TCDW ~ 33 K). Electric and magnetic fields have been used to manipulate spatial or time inversion symmetry, while the CDW in 2H-NbSe2 remains robust even under large magnetic fields on the order of tens of Tesla. However, magnetic-field-sensitive CDWs have been reported in few-layer NbSe2, where a weak magnetic field of approximately 30 mT can switch the electronic phase within the thin film, resulting in a supercurrent diode effect. This study investigates the strained 2H-NbSe2 exhibiting the 2*2 CDW phase. We utilize low-temperature (4.3 K) scanning tunneling microscopy and spectroscopy (STM/STS) in ultrahigh vacuum (UHV). STS maps reveal the coherence of the 2*2 CDW patterns. However, applying an out-of-plane magnetic field induces a dramatic transformation akin to that observed in 1T-NbSe2, shifting the metallic 2D CDW pattern to a 1D CDW pattern.
Keywords: Charge Density Wave; STM; STS; NbSe2