Jasnamol Palakkal
Recently two-dimensional (2D) magnets got attention for their new science and potentiality in spintronics devices. The 2D materials of the CrxTey type are reported to be ferromagnets with exotic nature and perpendicular magnetic anisotropy (PMA) [1]. Cr2Te3 is reported to be a 2D magnet, showing strong PMA whose TC can be tuned by Al-doping [1-3]. Tunable room-temperature ferromagnetism was reported in CrTe3, for which the TC is increased by decreasing the thickness [2]. Lately, CrTe2 ultrathin films were reported to be room-temperature intrinsic ferromagnet with strong PMA [3]. The strong PMA and weak interlayer coupling make even a monolayer of CrTe2 ferromagnetic, however, the TC decreases from 300 K to 200 K when the number of monolayers is reduced from twenty to one [3].
The Cr: Te ratio and the concentration of dopants are crucial in deciding the magnetism CrxTey materials. During the thin film deposition from the stoichiometric target by using a pulsed laser deposition (PLD), a selective deposition can take place which will leave the films non-stoichiometric. This is because of the comparably high evaporation temperature of elements like Cr and the low-temperature evaporation of Te. To complement elements in such a situation, we are modifying our PLD chamber to a hybrid PLD setup where Te (or any other chalcogens) can be supplied in the form of a molecular beam. Here, the advantage of using hybrid PLD over conventional MBE is that using any additional number of cations as a dopant or substitution is easier when using a PLD where a separate e-beam pocket or effusion cell is required for MBE.
In this talk, various defects of CrxTey thin films reported in the literature and their magnetic properties will be discussed. A technical introduction to the hybrid MBE-PLD setup and its scientific advantages will also be discussed.
[2] Y. Wen, Z. Liu, Y. Zhang, C. Xia, B. Zhai, X. Zhang, G. Zhai, C. Shen, P. He, R. Cheng, L. Yin, Y. Yao, M. Getaye Sendeku, Z. Wang, X. Ye, C. Liu, C. Jiang, C. Shan, Y. Long, J. He, Tunable Room-Temperature Ferromagnetism in Two-Dimensional Cr2Te3, Nano Letters, 20 (2020) 3130-3139.
[3] X. Zhang, Q. Lu, W. Liu, W. Niu, J. Sun, J. Cook, M. Vaninger, P.F. Miceli, D.J. Singh, S.-W. Lian, T.-R. Chang, X. He, J. Du, L. He, R. Zhang, G. Bian, Y. Xu, Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films, Nature Communications, 12 (2021) 2492.