Creation of a Field-Induced Co(II) Single-Ion Magnet by Doping into a Zn(II) Diamagnetic Metal-Organic Framework

Masanori Wakizaka; Ryuta Ishikawa; Hisaaki Tanaka; Shraddha Gupta; Shinya Takaishi; Masahiro Yamashita

doi:10.1002/smll.202301966

Creation of a Field-Induced Co(II) Single-Ion Magnet by Doping into a Zn(II) Diamagnetic Metal-Organic Framework

Small. 2023 Aug;19(32):e2301966. doi: 10.1002/smll.202301966. Epub 2023 May 13.

Authors

Masanori Wakizaka¹, Ryuta Ishikawa², Hisaaki Tanaka³, Shraddha Gupta⁴, Shinya Takaishi⁴, Masahiro Yamashita^{4

5}

Affiliations

¹ Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramaki-Aza-Aoba, Aoba-Ku, Sendai, 980-8578, Japan.
² Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-Ku, Fukuoka, 814-0180, Japan.
³ Department of Applied Physics, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya, 464.-8603, Japan.
⁴ Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Aoba-Ku, Sendai, 980-8578, Japan.
⁵ School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China.

PMID: 37178437
DOI: 10.1002/smll.202301966

Abstract

The combination of single-ion magnets (SIMs) and metal-organic frameworks (MOFs) is expected to produce new quantum materials. The principal issue to be solved in this regard is the development of new strategies for the synthesis of SIM-MOFs. This work demonstrates a new simple strategy for the synthesis of SIM-MOFs where a diamagnetic MOF is used as the framework into which the SIM sites are doped. 1, 0.5, and 0.2 mol% of the Co(II) ions are doped into the Zn(II) sites of [CH₆ N₃ ][Zn^II (HCOO)₃ ]. The doped Co(II) sites in the MOFs perform as SIM with a positive D term of zero-field splitting. The longest magnetic relaxation time is 150 ms (0.2 mol% Co) at 1.8 K under a static field of 0.1 T. Temperature dependency of the relaxation time suggests suppressing magnetic relaxation by reduction of spin-spin interaction upon doping in the rigid framework. Thus, this work represents a proof of concept for the creation of a single-ion doped magnet in the MOF. This simple synthetic strategy will be widely applied for the creation of quantum magnetic materials.

Keywords: cobalt(II); hybrid organic-inorganic perovskites; metal-organic frameworks; quantum magnetism; single-ion magnets.

Abstract

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