Signature of elementary excitations in Se-substituted layered triangular-lattice antiferromagnet CuCrS2

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Journal of Magnetism and Magnetic Materials, Volume 590
Geometrical spin frustration in a layered triangular-lattice system prohibits the long-range magnetic order and could give rise to unusual spin-disordered states of matter in which spins are strongly correlated and highly entangled with low-energy excitations. Here we investigate the low-temperature magnetic and specific heat properties of the layered triangular-lattice system CuCr(S1-xSex)2 within the entire Se-for-S substitution range. In magnetization measurements, the x = 0 phase exhibits a sharp cusp-like antiferromagnetic transition at 38 K, while for all the Se-substituted samples a broad maximum along with a spin-glass-like freezing at low temperatures is seen. The Curie-Weiss temperature systematically increases from −122 K for x = 0 to + 15 K for x = 1. These observations suggest that the magnetic ground state is determined by the competition between antiferromagnetic direct exchange interactions and ferromagnetic super-exchange interactions. For x = 0, the magnetic contribution to heat capacity exhibits a sharp jump at the magnetic transition temperature indicative of 3D long-range magnetic order, while for the x > 0 samples it increases smoothly across the magnetic transition range following a power-law (∼T2.1) behavior. All these results are in line with an existence of unusual gapless spin-liquid like excitations originating from the spin frustrations and competing nearest-neighbor interactions in CuCr(S,Se)2.
Funding Information: Prof. Karppinen acknowledges the funding from the Finnish Cultural Foundation, Project THERMOF (Electrical energy from waste heat using flexible metal-organic thermoelectric materials). This work made use of the RawMatters Finland infrastructure (RAMI) facilities at Aalto University. Publisher Copyright: © 2023 The Authors
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Tewari, G C, Sajida Kousar, H, Srivastava, D & Karppinen, M 2024, ' Signature of elementary excitations in Se-substituted layered triangular-lattice antiferromagnet CuCrS 2 ', Journal of Magnetism and Magnetic Materials, vol. 590, 171688 .