Intrinsic Magnetic Order of Chemically Exfoliated 2D Ruddlesden–Popper Organic–Inorganic Halide Perovskite Ultrathin Films. Issue 52 (26th November 2020)

• Record Type: Journal Article
• Authors: Kim, Ki‐Yeon; Park, Garam; Cho, Jaehun; Kim, Joonwoo; Kim, June‐Seo; Jung, Jinyong; Park, Kwonjin; You, Chun‐Yeol; Oh, In‐Hwan
• Is Part Of: Small. Volume 16:Issue 52(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-26
• Subjects: 2D magnets -- 2D Ruddlesden–Popper OIHPs -- chemical exfoliation -- spin coating; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202005445
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Thin film fabrication of 2D layered organic–inorganic hybrid perovskites (2D‐OIHPs) for spintronic applications has been attempted using solution‐based process like Langmuir–Blodgett technique. However, monolayer or few‐layered 2D magnets are not yet realized, even though a wide spectrum of 2D Ruddlesden–Popper (RP) OIHPs are known as quasi‐2D Heisenberg magnets in bulk compounds. Here, chemical exfoliation by solvent engineering is applied to successfully synthesize large‐sized, few unit‐cell‐thick 2D RP‐OIHPs. Comprehensive structural characterization reveals that binary co‐solvents with high relative polarity in spin coating technique are the most effective among nine kinds of solvents. Above all, this enables few‐layered 2D RP‐OIHP ultrathin films sustaining their intrinsic magnetic order. It is found that XY‐like magnetic anisotropy driven by Jahn–Teller effect responsible for ferromagnetism in seven‐layered (C6 H5 CH2 CH2 NH3 )2 CuCl4 ultrathin films remains very robust, whereas Ising‐like dipolar anisotropy responsible for canted antiferromagnetism in ten‐layered (C6 H5 CH2 CH2 NH3 )2 MnCl4 ultrathin films is greatly reduced. It is expected that ferromagnetism even at monolayer limit should be possible by means of further sophisticated solvent engineering as long as Jahn–Teller effect is active. The chemical exfoliation using solvent engineering unambiguously can bring about a new breakthrough in the development of 2D RP‐OIHP van der Waals magnets for ultrahigh energy‐efficient spintronic, opto‐spintronic devices. Abstract : Few‐layered, 2D Ruddlesden–Popper organic–inorganic hybrid perovskites with intrinsic magnetic moment are successfully self‐assembled via the combination of solvent engineering and spin coating techniques. Binary co‐solvent method is found to produce ultrathin films with better surface coverage and uniformity than single‐solvent method. Owing to robust Jahn–Teller effect, seven‐layered (C6 H5 CH2 CH2 NH3 )CuCl4 ultrathin films have phase transition temperature and magnetization comparable to bulk counterparts.