epitaxial thin films*

     The ionic gate technique is a strong method to manipulate the properties of materials, by which we can modify the carrier number significantly. A successful example is the ionic-gate-induced superconductivity in a band insulator SrTiO₃ [1]. In the case of magnetism, people could successfully tune the Curie temperature of Fe₃GeTe₂ [2], switch an artificial lattice antiferromagnet into ferromagnet [3], and also modify the Curie temperature and magnetic anisotropy of Cr₃Te₄ [4]. Here, we focus on Cr-intercalated NbSe₂ as a target material system. We have reported in the previous APS March Meeting that the Cr_1/3NbSe₂ epitaxial thin films grown by molecular-beam epitaxy exhibit easy-plane ferromagnetism while the Cr_1/4NbSe₂ thin films do not show ferromagnetism [5]. We also discussed the importance of the carrier number for the emergence of the long-range magnetic order in Cr-intercalated NbSe₂ through the series of the vacuum-annealing experiments [5]. In this study, we applied the ion-gating technique to tune the carrier number of the Cr_1/4NbSe₂ thin films, and observed large modulation in the transport properties including the emergence of the anomalous Hall effect, demonstrating that originally non-ferromagnetic Cr_1/4NbSe₂ could be tuned to be ferromagnetic via electron doping.

 

[1] K. Ueno et al. Nat. Mater., 7, 855 (2008).

[2] Y. Deng et al. Nature, 563, 94 (2018).

[3] Q. Yang et al. Nat. Commun., 9, 991 (2018).

[4] H. Matsuoka et al. arXiv:2304.11890 (2023).

[5] X. Huang et al. D39.00003, APS March Meeting 2023.