Fermi surface of the flat-band intermetallics $A\mathrm{P}{\mathrm{d}}_3$ $\left(A=\mathrm{Pb},\mathrm{Sn}\right)$

Journal Article · Wed Apr 03 00:00:00 EDT 2019 · Physical Review Materials

DOI:https://doi.org/10.1103/PhysRevMaterials.3.041201· OSTI ID:1594438

Wei, Kaya ^[1]; Chen, Kuan-Wen ^[1]; Neu, Jennifer N. ^[1]; Lai, You ^[1]; Chappell, Greta L. ^[1]; Nolas, George S. ^[2]; Graf, David E. ^[1]; Xin, Yan ^[1]; Balicas, Luis ^[1]; Baumbach, Ryan E. ^[1]; Siegrist, Theo ^[1]

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1. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
2. Univ. of South Florida, Tampa, FL (United States). Dept. of Physics

The intermetallic phases APd₃ (A = Pb, Sn) were recently predicted to host an unconventional combination of unique electronic structure features, namely, flat bands near the Fermi energy coexisting with topologically protected surface states at the Gamma point. These features each could independently produce alternative electronic states, including electronically or magnetically ordered states coexisting with unconventional edge dominated transport and a significantly large thermopower coexisting with topological characteristics. To explore these expectations, we report the synthesis, structural/chemical characterization, electrical and thermal transport properties, magnetic torque (up to 45 T), and Fermi surface mapping for single crystals produced using the Czochralski technique. X-ray diffraction and scanning transmission electron microscope measurements establish the absence of defects, while small measured values of the thermopower indicate that the Fermi level is located away from the flat-band region. The electronic properties are further clarified by the topography of the Fermi surfaces, measured through the de Haas–van Alphen effect. We find that the Fermi levels are placed at higher energy values than the original ones resulting from the density functional theory calculations, 54 meV higher for PbPd₃ and 68 meV higher for SnPd₃. Furthermore, the molten flux method was used to synthesize PbPd₃, yielding nearly identical Fermi surfaces between the specimens grown using different synthesis techniques, indicating the robustness of the Fermi level position. According to the density functional theory calculations, the flat band is mainly formed by the 4d bands of Pd. Thus, we propose monovalent doping on the Pb/Sn site as a viable approach to accessing the flat band while maintaining the unique band structure features of these compounds.

• Research Organization: Florida State Univ., Tallahassee, FL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
• Grant/Contract Number: SC0002613
• OSTI ID: 1594438
• Alternate ID(s): OSTI ID: 1504801
• Journal Information: Physical Review Materials, Vol. 3, Issue 4; ISSN 2475-9953
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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