A Natural 2D Heterostructure [Pb3.1Sb0.9S4][Au x Te2–x ] with Large Transverse Nonsaturating Negative Magnetoresistance and High Electron Mobility

• Published in: Journal of the American Chemical Society Vol. 141; no. 18; pp. 7544 - 7553
• Main Authors: Chen, Haijie, He, Jiangang, Malliakas, Christos D, Stoumpos, Constantinos C, Rettie, Alexander J. E, Bao, Jin-Ke, Chung, Duck Young, Kwok, Wai-Kwong, Wolverton, Christopher, Kanatzidis, Mercouri G
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.05.2019; American Chemical Society (ACS)
• Subjects: 2D materials; ambient temperature; electrons; gold; high mobility; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; magnetoresistance; X-ray diffraction
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.9b02599

We report the two-dimensional (2D) natural heterostructure [Pb3.1Sb0.9S4]­[Au x Te2–x ] (x = 0.52–0.36) which shows anomalous, transverse nonsaturating negative magnetoresistance (MR). For x = 0.52, the material has a commensurately modulated structure with alternating [Pb3.1Sb0.9S4] rocksalt layers and atomically thin [Au x Te2–x ] sheets, as determined by single-crystal X-ray diffraction using a (3 + 1)-dimensional space group; for other x compositions, the modulated structure is absent and the Au and Te atoms are disordered. The transport properties in this system at low temperature (<100 K) are dominated by an unusual 2D hopping mechanism, while at room temperature a high carrier mobility of ∼1352 cm2 V–1 s–1 is obtained (x = 0.36). The confined electrons within the [Au x Te2–x ] layers are also exposed to interlayer coupling with the insulating [Pb3.1Sb0.9S4] layers, and as a result, the properties of the heterostructures emerge not only from the constituent layers but also the interactions between them. Furthermore, the various Au and Te coordination patterns found in the [Au x Te2–x ] sheets as a function of x further contribute to a unique electronic structure that leads to the anomalous nonsaturating negative MR with different field dependent behaviors. First-principles calculations indicate that the [Au x Te2–x ] sheets are responsible for the unusual electrical transport properties in this 2D system.