Emergence of a Non-Van der Waals Magnetic Phase in a Van der Waals Ferromagnet |
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Authors: | Bikash Das Subrata Ghosh Shamashis Sengupta Pascale Auban-Senzier Miguel Monteverde Tamal Kumar Dalui Tanima Kundu Rafikul Ali Saha Sujan Maity Rahul Paramanik Anudeepa Ghosh Mainak Palit Jayanta K Bhattacharjee Rajib Mondal Subhadeep Datta |
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Affiliation: | 1. School of Physical Sciences, Indian Association for the Cultivation of Science, 2A & B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032 India;2. Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, 91405 France;3. Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay, 91405 France;4. Department of Microbial and Molecular Systems, Centre for Membrane Separations, Adsorption, Catalysis and Spectroscopy for Sustainable Solutions (cMACS), KU Leuven, Celestijnenlaan 200F, Leuven, 3001 Belgium;5. UGC-DAE Consortium for Scientific Research, Kolkata Centre, Bidhannagar, Kolkata, 700 106 India |
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Abstract: | Manipulation of long-range order in 2D van der Waals (vdW) magnetic materials (e.g., CrI3, CrSiTe3 ,etc.), exfoliated in few-atomic layer, can be achieved via application of electric field, mechanical-constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the exposure in the ambient condition and hydrolysis in the presence of water/moisture causes degradation in magnetic nanosheets that, in turn, affects the nanoelectronic /spintronic device performance. Counterintuitively, the current study reveals that exposure to the air at ambient atmosphere results in advent of a stable nonlayered secondary ferromagnetic phase in the form of Cr2Te3 (TC2 ≈160 K) in the parent vdW magnetic semiconductor Cr2Ge2Te6 (TC1 ≈69 K). The coexistence of the two ferromagnetic phases in the time elapsed bulk crystal is confirmed through systematic investigation of crystal structure along with detailed dc/ac magnetic susceptibility, specific heat, and magneto-transport measurement. To capture the concurrence of the two ferromagnetic phases in a single material, Ginzburg-Landau theory with two independent order parameters (as magnetization) with a coupling term can be introduced. In contrast to the rather common poor environmental stability of the vdW magnets, the results open possibilities of finding air-stable novel materials having multiple magnetic phases. |
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Keywords: | 2D vdW materials ferromagnetic ordering magnetic anisotropy magneto-transport |
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