High-Pressure Synthesis of Magnetic Neodymium Polyhydrides

Di Zhou; Dmitrii V Semenok; Hui Xie; Xiaoli Huang; Defang Duan; Alex Aperis; Peter M Oppeneer; Michele Galasso; Alexey I Kartsev; Alexander G Kvashnin; Artem R Oganov; Tian Cui

doi:10.1021/jacs.9b10439

High-Pressure Synthesis of Magnetic Neodymium Polyhydrides

J Am Chem Soc. 2020 Feb 12;142(6):2803-2811. doi: 10.1021/jacs.9b10439. Epub 2020 Feb 3.

Authors

Di Zhou¹, Dmitrii V Semenok², Hui Xie¹, Xiaoli Huang¹, Defang Duan¹, Alex Aperis³, Peter M Oppeneer³, Michele Galasso², Alexey I Kartsev^{4

5}, Alexander G Kvashnin², Artem R Oganov^{2

6}, Tian Cui^{1

7}

Affiliations

¹ State Key Laboratory of Superhard Materials, College of Physics , Jilin University , Changchun 130012 , China.
² Skolkovo Institute of Science and Technology , Skolkovo Innovation Center, 3 Nobel Street , Moscow 121205 , Russia.
³ Department of Physics and Astronomy , Uppsala University , P.O. Box 516, Uppsala SE-75120 , Sweden.
⁴ Computing Center of Far Eastern Branch of the Russian Academy of Sciences (CC FEB RAS) , Khabarovsk 680000 , Russian Federation.
⁵ School of Mathematics and Physics , Queen's University Belfast , Belfast , Northern Ireland BT7 1NN , United Kingdom.
⁶ International Center for Materials Discovery , Northwestern Polytechnical University , Xi'an 710072 , China.
⁷ School of Physical Science and Technology , Ningbo University , Ningbo 315211 , China.

PMID: 31967807
DOI: 10.1021/jacs.9b10439

Abstract

Ongoing search for room-temperature superconductivity is inspired by the unique properties of the electron-phonon interaction in metal superhydrides. Encouraged by the recently found highest-T_C superconductor fcc-LaH₁₀, here we discover several superhydrides of another lanthanoid, neodymium. We identify three novel metallic Nd-H phases at pressures ranging from 85 to 135 GPa: I4/mmm-NdH₄, C2/c-NdH₇, and P6₃/mmc-NdH₉, synthesized by laser-heating metal samples in NH₃BH₃ media for in situ generation of hydrogen. A lower trihydride Fm3̅m-NdH₃ is found at pressures from 2 to 52 GPa. I4/mmm-NdH₄ and C2/c-NdH₇ are stable from 135 to 85 GPa, and P6₃/mmc-NdH₉ is stable from 110 to 130 GPa. Measurements of the electrical resistance of NdH₉ demonstrate a possible superconducting transition at ∼4.5 K in P6₃/mmc-NdH₉. Our theoretical calculations predict that all of the neodymium hydrides have antiferromagnetic order at pressures below 150 GPa and represent one of the first discovered examples of strongly correlated superhydrides with large exchange spin-splitting in the electronic band structure (>450 meV). The critical Néel temperatures for new neodymium hydrides are estimated using the mean-field approximation to be about 4 K (NdH₄), 251 K (NdH₇), and 136 K (NdH₉).