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Molybdenum chloride double perovskites: dimensionality control of optical and magnetic properties
Devesh Chandra Binwal1, Prashurya Pritam Mudoi1, Debendra Prasad Panda2
1New Chemistry Unit, International Centre for Materials Science, School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research Jakkur P.O. Bangalore-560064 India pvishnoi@jncasr.ac.in.
Abstract:
Halide double perovskites are a promising class of semiconducting materials for applications in solar cells and other optoelectronic devices. Recently, there has been a surge of interest in these materials to study phenomena beyond optoelectronics, especially magnetism. Here, we report three new Mo3+ (4d3) based chloride double perovskites: a 3-D rock-salt ordered Cs2NaMoCl6, a 1-D chain (MA)2AgMoCl6 and a Dion-Jacobson type 2-D layered (1,4-BDA)2AgMoCl8 (MA = methylammonium; 1,4-BDA = 1,4-butanediammonium). Their structures and dimensionalities can be tuned by means of the A-cation. The measured bandgaps are relatively narrow (2.0-2.1 eV) which show a blueshift on reducing the dimensionality. At low temperatures, we observe antiferromagnetic coupling between the nearest-neighbour Mo3+ ions in all these systems. Cs2NaMoCl6 shows stronger coupling with a frustration index f of 5 which we attribute to the geometrically frustrating fcc lattice of Mo3+ ions. This work expands the scope of halide double perovskites beyond main group metals and beyond optoelectronics, and we hope that it will lead to future developments in magnetic halide perovskites.
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