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arXiv · 2308.16338

Formation of random singlets in the nanocrystalline quasi-one-dimensional spin-1/2 antiferromagnet Sr21Bi8Cu2(CO3)2O41

Yanbo Guo·Xinzhe Hu·Hasan Siddiquee·Kapila Kumarasinghe·Swapnil M. Yadav·Eun Sang Choi·Yasuyuki Nakajima·Yasumasa Takano
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Abstract

Induced by quenched disorder, random-singlet states occur in a variety of low-dimensional spin-1/2 antiferromagnets, some of them candidates for quantum spin liquids. Here we report measurements of the specific heat, magnetization, and magnetic susceptibility of nanocrystalline Sr21Bi8Cu2(CO3)2O41, a quasi-one-dimensional spin-1/2 antiferromagnet with alternating bonds. The results uncover the predominant presence of random-singlet spin pairs in this material, with a logarithmic probability distribution, P(J), of the renormalized, emergent exchange interaction, J, in zero magnetic field and P(J) proportional to 1/J in magnetic fields. We postulate that these unexpected J dependences, in contrast to the usual P(J) \propto 1/$J^γ$ with 0 < $γ$ < 1, and possibly also the dichotomy, arise from the finite size of the nanocrystals. Scaling functions for the specific heat and magnetization reproduce our magnetocaloric-effect data, with no adjustable parameters.

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Yanbo Guo, Xinzhe Hu, Hasan Siddiquee, Kapila Kumarasinghe, Swapnil M. Yadav, Eun Sang Choi, Yasuyuki Nakajima, Yasumasa Takano. 2023-09-10. Formation of random singlets in the nanocrystalline quasi-one-dimensional spin-1/2 antiferromagnet Sr21Bi8Cu2(CO3)2O41. https://arxiv.org/abs/2308.16338

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