High-pressure synthesis and physical properties of the single-layer nickelate oxychalcogenides <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">B</mi><msub><mi mathvariant="normal">a</mi><mn>2</mn></msub><mi>Ni</mi><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mi mathvariant="normal">C</mi><msub><mi mathvariant="normal">u</mi><mn>2</mn></msub><msub><mi>X</mi><mn>2</mn></msub></mrow></math> (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>X</mi><mo>=</mo><mi mathvariant="normal">S</mi></mrow></math> and Se)

Zhen Dong; Xiao Wang; Yingying Cao; Wenhui Liu; Yu Liu; Xubin Ye; Guangyang Dai; Guoxiang Guan; Zhiwei Hu; Chang-Yang Kuo; Chien-Te Chen; Wenmin Li; Yongbing Xue; Youwen Long; Xiancheng Wang; Changqing Jin

doi:10.1103/49kv-rlm7

High-pressure synthesis and physical properties of the single-layer nickelate oxychalcogenides $B a_{2} Ni O_{2} C u_{2} X_{2}$ ( $X = S$ and Se)

Zhen Dong^1,2,*, Xiao Wang ^2,*, Yingying Cao^2,*, Wenhui Liu², Yu Liu², Xubin Ye ³, Guangyang Dai ², Guoxiang Guan ², Zhiwei Hu⁴ et al.

Chang-Yang Kuo^5,6, Chien-Te Chen⁶, Wenmin Li ^2,†, Yongbing Xue^1,‡, Youwen Long³, Xiancheng Wang^3,§, and Changqing Jin^3,¶

¹College of Chemical Engineering and Technology, Taiyuan University of Science and Technology, Taiyuan 030024, China
²Institute of Quantum Materials and Physics, Henan Academy of Sciences, Zhengzhou 450046, China
³Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
⁴Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
⁵Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
⁶National Synchrotron Radiation Research Center (NSRRC), Hsinchu Science Park, Hsinchu 300092, Taiwan

^*These authors contributed equally to this work
^†Contact author: wmli@hnas.ac.cn
^‡Contact author: tykjdxxyb@163.com
^§Contact author: wangxiancheng@iphy.ac.cn
^¶Contact author: Jin@iphy.ac.cn

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Phys. Rev. B 113, 174441 – Published 29 May, 2026

DOI: https://doi.org/10.1103/49kv-rlm7

Abstract

New single-layer nickelate oxychalcogenides $B a_{2} Ni O_{2} C u_{2} X_{2}$ ( $X = S$ and Se) were successfully synthesized by using a high-pressure high-temperature method. They crystallize into the tetragonal space group $I 4$ /mmm with alternating $Ni O_{2}$ square planar and $C u_{2} S e_{2}$ antifluorite layers along the $c$ direction. High-pressure synchrotron x-ray diffraction manifests that the $B a_{2} Ni O_{2} C u_{2} S e_{2}$ can be fairly compressed along the $c$ direction, whereas the $a b$ plane is quite rigid, corresponding to its layered feature. The valence states of $N i^{2 +}$ and $C u^{1 +}$ were validated from both bond valence sums and x-ray absorption spectroscopy. The magnetization of $B a_{2} Ni O_{2} C u_{2} S_{2}$ follows the Curie-Weiss law, whereas a spin-glass-like behavior emerges below $T_{sg} = 5$ K. On the other hand, $B a_{2} Ni O_{2} C u_{2} S e_{2}$ experiences a low-dimensional antiferromagnetic transition at $T_{N} = 200$ K. The resistivity of both compounds follows the thermal activation model at elevated temperatures and follows the three-dimensional variable-range hopping model at low temperatures, indicating the semiconducting or insulating nature. DFT+ $U$ calculations indicate that weak antiferromagnetic coupling in the $Ni O_{2}$ layer suppresses the Fermi surface, thereby opening a gap in the electronic structure. The electrical resistance gradually decreases under high pressure, no superconductivity was observed up to 21.4 GPa. This work provides an insight to explore new layered nickelates with emergent physical properties and potential superconductivity.

Physical Review B

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High-pressure synthesis and physical properties of the single-layer nickelate oxychalcogenides $B a_{2} Ni O_{2} C u_{2} X_{2}$ ( $X = S$ and Se)

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High-pressure synthesis and physical properties of the single-layer nickelate oxychalcogenides Ba2NiO2Cu2X2 (X=S and Se)

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High-pressure synthesis and physical properties of the single-layer nickelate oxychalcogenides $B a_{2} Ni O_{2} C u_{2} X_{2}$ ( $X = S$ and Se)