High mobility in a van der Waals layered antiferromagnetic metal

Abstract

Magnetic van der Waals (vdW) materials have been heavily pursued for fundamental physics as well as for device design. Despite the rapid advances, so far magnetic vdW materials are mainly insulating or semiconducting, and none of them possesses a high electronic mobilitya property that is rare in layered vdW materials in general. The realization of a magnetic high-mobility vdW material would open the possibility for novel magnetic twistronic or spintronic devices.Here we report very high carrier mobility in the layered vdW antiferromagnet GdTe 3. The electron mobility is beyond 60,000 cm 2 V -1 s -1 , which is the highest among all known layered magnetic materials, to the best of our knowledge. Among all known vdW materials, the mobility of bulk GdTe 3 is comparable to that of black phosphorus, and is only surpassed by graphite. By mechanical exfoliation, we further demonstrate that GdTe 3 can be exfoliated to ultrathin flakes of three monolayers, and that the magnetic order and relatively high mobility is retained in ~20-nm-thin flakes.VdW materials are the parent compounds of two-dimensional (2D) materials, which are currently actively studied for new device fabrications (1) involving the creation of heterostructure stacks (2) or twisted bilayers (3) of 2D building blocks. Magnetic vdW materials have recently led to the observation of intrinsic magnetic order in atomically thin layers (4-12), which was followed by exciting discoveries of giant tunneling magnetoresistance (13-16) and tunable magnetism (17)(18)(19) in such materials.So far, the known magnetic vdW materials (ferro-or antiferromagnetic) that can be exfoliated are limited to a few examples, such as: CrI3 (4), Cr2Ge2Te6 (5), FePS3 (6,7), CrBr3 (8, 9), CrCl3 (10-12), Fe3GeTe2 (17,20), and RuCl3 (21-23). Out of these, only Fe3GeTe2 is a metallic ferromagnet and there is no known vdW-based 2D antiferromagnetic metal. Moreover, no evidence of high carrier mobilities has been reported in any of these exfoliated thin materials or even in their bulk vdW crystals. In general, high mobility is limited to very few vdW materials, such as graphite (24) and black phosphorus (25). A material with high electronic mobility and a corresponding high mean-free-path (MFP), might be critical for potential magnetic "twistronic" devices (3) where a large MFP could enable interesting phenomena in a Moiré-supercell induced flat band. In addition, conducting antiferromagnetic materials are the prime candidates for high-speed antiferromagnetic spintronic devices (26). Here we report the realization of a very high electronic mobility in a vdW layered antiferromagnet, GdTe3, both in bulk and exfoliated thin flakes.We chose to study GdTe3, since rare-earth tritellurides (RTe3, R = La-Nd, Sm, and Gd-Tm) are structurally related to topological semimetal ZrSiS (27,28), while being known to exhibit an incommensurate charge density wave (CDW) (29-31), rich magnetic properties (32), and becoming superconducting under high-pressure (R = Gd, Tb and Dy) (33). Combined, these properties ...

The Role of Delocalized Chemical Bonding in Square-Net-Based Topological Semimetals

“…[75][76][77][78] Nonetheless, the CDW does not result in a semiconducting state and steep bands remain after the distortion. 74 Therefore, the tolerance factor can be used to identify materials with exciting electronic properties, even if a structural distortion exists. Our analysis indicates the similar Nd 2 Te 5 structure type (t values between 0.90 and 0.91) to be a logical next step for future studies in lanthanide telluride systems.…”

Recent Advances in 2D Rare Earth Materials

“…As shown in Figure 2a,b, Schoop et al recently synthesized ≈8 mm × ≈8 mm high-quality GdTe 3 crystals by the self-flux method with Te and Gd sources. [69] Self-flux method is an effective way for single-crystal growth, which uses molten solids as solvents or fluxes. [89] In the GdTe 3 case, Te has low melting point about 452 °C, which can act not only as reactants, but also as solvents to provide reactive flux.…”

“…[34] As shown in Figure 3c,d, after the sputtering of Gd atoms to the heated (111) surface of Si, GdSi 2 layered structures are formed with the delivering of the nearest Si atoms in the silicide, forming c) Reproduced with permission. [69] Copyright 2020, American Association for the Advancement of Science. d) Schematic diagram illustrates the synthesis of RE-coordinated BP nanosheets.…”

“…[35,67,68] Owing to unique structure related to topological semimetal, some of them possess CDW properties and become superconducting under high pressure. [35,36,69] For example, both downconversion (DC) in the near-infrared (NIR) region and upconversion (UC) in the visible (VIR) red region were realized in TMDs first by doping MoS 2 with Er 3+ ions by Hao et al [70] Transformation of 3D antiferromagnetism (AFM) into 2D FM of GdSi 2 and EuSi 2 was demonstrated by Storchak et al [34] Light-induced CDW was observed in 2D LaTe 3 by Gedik et al [35,36] Van der Waals (vdW) materials with both high carrier mobility over 60 000 cm 2 V −1 s −1 and magnetic order were reported in GdTe 3 by Schoop et al [69] Usually, vdW materials with magnetic order have a extremely low electronic mobility and are either insulators or semiconductors. The realization of high-mobility vdW materials like the above 2D RE material GdTe 3 which possesses magnetic order can have promising potential for novel magnetic spintronic applications.…”

Multifunctional Antiferromagnetic Materialswith Giant Piezomagnetism and Noncollinear Spin Current

“…Being atomically thin, 2D materials are easier to engineer via gate modulation 12,13 , strain 14 and proximity effect 15 . Recent discoveries of atomic-thin ferromagnetic [16][17][18][19][20] and antiferromagnetic (AFM) materials [21][22][23][24][25][26] further enriched the 2D material family and opened a new era for spintronics and valleytronics with nonvolatile magnetic information storage. Moreover, 2D AFM materials possess many other desirable features such as higher-speed operation and lower-energy consumption as proposed in the AFM spintronics [27][28][29][30] .…”