Entropy-Assisted, Long-Period Stacking of Honeycomb Layers in an AlB2-Type Silicide

Leonie Spitz; Takuya Nomoto; Shunsuke Kitou; Hironori Nakao; Akiko Kikkawa; Sonia Francoual; Yasujiro Taguchi; Ryotaro Arita; Yoshinori Tokura; Taka-Hisa Arima; Max Hirschberger

doi:10.1021/jacs.2c04995

Entropy-Assisted, Long-Period Stacking of Honeycomb Layers in an AlB₂-Type Silicide

J Am Chem Soc. 2022 Sep 21;144(37):16866-16871. doi: 10.1021/jacs.2c04995. Epub 2022 Sep 6.

Authors

Leonie Spitz¹, Takuya Nomoto², Shunsuke Kitou¹, Hironori Nakao³, Akiko Kikkawa¹, Sonia Francoual⁴, Yasujiro Taguchi¹, Ryotaro Arita^{1

2}, Yoshinori Tokura^{1

2

5}, Taka-Hisa Arima^{1

6}, Max Hirschberger^{1

2}

Affiliations

¹ RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
² Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
³ Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan.
⁴ Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
⁵ Tokyo College, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
⁶ Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan.

PMID: 36066406
DOI: 10.1021/jacs.2c04995

Abstract

Configurational entropy can impact crystallization processes, tipping the scales between structures of nearly equal internal energy. Using alloyed single crystals of Gd₂PdSi₃ in the AlB₂-type structure, we explore the formation of complex layer sequences made from alternating, two-dimensional triangular and honeycomb slabs. A four-period and an eight-period stacking sequence are found to be very close in internal energy, the latter being favored by entropy associated with covering the full configuration space of interlayer bonds. Possible consequences of polytype formation on magnetism in Gd₂PdSi₃ are discussed.