Spin-Glass States Generated in a van der Waals Magnet by Alkali-Ion Intercalation

Safe Khan; Eva S Y Aw; Liam A V Nagle-Cocco; Aakanksha Sud; Sukanya Ghosh; Mohammed K B Subhan; Zekun Xue; Charlie Freeman; Dimitrios Sagkovits; Araceli Gutiérrez-Llorente; Ivan Verzhbitskiy; Daan M Arroo; Christoph W Zollitsch; Goki Eda; Elton J G Santos; Sian E Dutton; Steven T Bramwell; Chris A Howard; Hidekazu Kurebayashi

doi:10.1002/adma.202400270

Spin-Glass States Generated in a van der Waals Magnet by Alkali-Ion Intercalation

Adv Mater. 2024 Sep;36(36):e2400270. doi: 10.1002/adma.202400270. Epub 2024 Jul 22.

Authors

Safe Khan¹, Eva S Y Aw², Liam A V Nagle-Cocco³, Aakanksha Sud^{4

5}, Sukanya Ghosh⁶, Mohammed K B Subhan², Zekun Xue¹, Charlie Freeman¹, Dimitrios Sagkovits¹, Araceli Gutiérrez-Llorente^{1

7}, Ivan Verzhbitskiy⁸, Daan M Arroo⁹, Christoph W Zollitsch¹, Goki Eda^{8

10

11}, Elton J G Santos^{6

12

13}, Sian E Dutton³, Steven T Bramwell¹, Chris A Howard², Hidekazu Kurebayashi^{1

14

15}

Affiliations

¹ London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
² Department of Physics & Astronomy, University College London, London, WC1H 0AH, UK.
³ Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
⁴ RIEC, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai, 980-0812, Japan.
⁵ FRIS, Tohoku University, 6-3, Aramaki, Aoba-Ku, Sendai, 980-0845, Japan.
⁶ Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK.
⁷ Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, Madrid, 28933, Spain.
⁸ Physics Department, National University of Singapore, Singapore 117551, Singapore.
⁹ Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
¹⁰ Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore.
¹¹ Centre for Advanced 2D Materials, National University of Singapore, Singapore, 117542, Singapore.
¹² Higgs Centre for Theoretical Physics, The University of Edinburgh, Edinburgh, EH9 3FD, UK.
¹³ Donostia International Physics Center, Donostia-San Sebastián, 20018, Spain.
¹⁴ WPI-AIMR, Tohoku University, 2-1-1, Katahira, Sendai, 980-8577, Japan.
¹⁵ Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK.

PMID: 39036829
DOI: 10.1002/adma.202400270

Abstract

Tuning magnetic properties in layered van der Waals (vdW) materials has captured significant attention due to the efficient control of ground states by heterostructuring and external stimuli. Electron doping by electrostatic gating, interfacial charge transfer, and intercalation is particularly effective in manipulating the exchange and spin-orbit properties, resulting in a control of Curie temperature (T_C) and magnetic anisotropy. Here, an uncharted role of intercalation is discovered to generate magnetic frustration. As a model study, Na atoms are intercalated into the vdW gaps of pristine Cr₂Ge₂Te₆ (CGT) where generated magnetic frustration leads to emerging spin-glass states coexisting with a ferromagnetic order. A series of dynamic magnetic susceptibility measurements/analysis confirms the formation of magnetic clusters representing slow dynamics with a distribution of relaxation times. The intercalation also modifies other macroscopic physical parameters including the significant enhancement of T_C from 66 to 240 K and the switching of magnetic easy-hard axis direction. This study identifies intercalation as a unique route to generate emerging frustrated spin states in simple vdW crystals.

Keywords: 2D materials; intercalation; magnetic frustration; magnetic materials; spin glass.

Abstract

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