Pervasive beyond Room-Temperature Ferromagnetism in a Doped van der Waals Magnet

Xiang Chen; Yu-Tsun Shao; Rui Chen; Sandhya Susarla; Tom Hogan; Yu He; Hongrui Zhang; Siqi Wang; Jie Yao; Peter Ercius; David A Muller; Ramamoorthy Ramesh; Robert J Birgeneau

doi:10.1103/PhysRevLett.128.217203

Pervasive beyond Room-Temperature Ferromagnetism in a Doped van der Waals Magnet

Phys Rev Lett. 2022 May 27;128(21):217203. doi: 10.1103/PhysRevLett.128.217203.

Authors

Xiang Chen^{1

2}, Yu-Tsun Shao³, Rui Chen^{1

4}, Sandhya Susarla^{1

4}, Tom Hogan⁵, Yu He^{1

2

6}, Hongrui Zhang⁴, Siqi Wang⁷, Jie Yao^{1

4}, Peter Ercius⁸, David A Muller^{3

9}, Ramamoorthy Ramesh^{1

2

4}, Robert J Birgeneau^{1

2

4}

Affiliations

¹ Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, USA.
² Physics Department, University of California, Berkeley, California 94720, USA.
³ School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.
⁴ Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
⁵ Quantum Design, Inc., San Diego, California 92121, USA.
⁶ Department of Applied Physics, Yale University, New Haven, Connecticut, 06511, USA.
⁷ NSF Nanoscale Science and Engineering Center (NSEC), 3112 Etcheverry Hall, University of California, Berkeley, California 94720, USA.
⁸ The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
⁹ Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, USA.

PMID: 35687434
DOI: 10.1103/PhysRevLett.128.217203

Abstract

The existence of long-range magnetic order in low-dimensional magnetic systems, such as the quasi-two-dimensional van der Waals (vdW) magnets, has attracted intensive studies of new physical phenomena. The vdW Fe_{N}GeTe_{2} (N=3, 4, 5; FGT) family is exceptional, owing to its vast tunability of magnetic properties. In particular, a ferromagnetic ordering temperature (T_{C}) above room temperature at N=5 (F5GT) is observed. Here, our study shows that, by nickel (Ni) substitution of iron in F5GT, a record high T_{C}=478(6) K is achieved. Importantly, pervasive, beyond room-temperature ferromagnetism exists in almost the entire doping range of the phase diagram of Ni-F5GT. We argue that this striking observation in Ni-F5GT can be possibly due to several contributing factors, including increased 3D magnetic couplings due to the structural alterations.