Gapless fermionic excitation in the antiferromagnetic state of ytterbium zigzag chain

The emergence of charge-neutral fermionic excitations in magnetic systems is one of the unresolved issues in recent condensed matter physics. This type of excitations has been observed in various systems, such as low-dimensional quantum spin liquids, Kondo insulators, and antiferromagnetic insulators. Here, we report the presence of a pronounced gapless spin excitation in the low-temperature antiferromagnetic state of YbCuS2 semiconductor, where trivalent ytterbium atoms form a zigzag chain structure. We confirm the presence of this gapless excitations by a combination of experimental probes, namely 63/65Cu-nuclear magnetic resonance and nuclear quadrupole resonance, as well as specific heat measurements, revealing a linear low-temperature behavior of both the nuclear spin-lattice relaxation rate 1/T1 and the specific heat. This system provides a platform to investigate the origin of gapless excitations in spin chains and the relationship between emergent fermionic excitations and frustration.

Hori, F; Kinjo, K; Kitagawa, S; Ishida, K; Mizutani, S; Yamamoto, R; Ohmagari, Y; Onimaru, T

Gapless fermionic excitation in the antiferromagnetic state of ytterbium zigzag chain Journal Article

In: Communications Materials, vol. 4, pp. 55, 2023.

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