Bulk excitations in ultraclean $α$-RuCl$_3$: Quantitative evidence for Majorana dispersions in a Kitaev quantum spin liquid
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arXiv
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| Autores principales: | , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866909626406010880 |
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| author | Imamura, Kumpei Namba, Ryuichi Ishioka, Riku Ishihara, Kota Matsuda, Yuji Lee, Seunghun Moon, Eun-Gook Hashimoto, Kenichiro Shibauchi, Takasada |
| author_facet | Imamura, Kumpei Namba, Ryuichi Ishioka, Riku Ishihara, Kota Matsuda, Yuji Lee, Seunghun Moon, Eun-Gook Hashimoto, Kenichiro Shibauchi, Takasada |
| contents | The spin-orbit coupled Mott insulator $α$-RuCl$_3$ has emerged as a prime candidate for realizing the Kitaev quantum spin liquid (KQSL), characterized by Majorana quasiparticles, whose edge states exhibit a distinctive half-integer quantized thermal Hall conductivity. However, its van der Waals nature makes its thermal Hall response highly sensitive to structural disorder, leading to sample-dependent variations. Here, we investigate low-energy bulk excitations in the field-induced quantum disordered (FIQD) state of newly available ultraclean single crystals of $α$-RuCl$_3$. High-resolution specific heat measurements under in-plane magnetic field rotation reveal an anisotropic excitation gap, whose field dependence is consistent with the Majorana gap in the KQSL state. Remarkably, when the field aligns with Ru-Ru bond directions, we observe gapless excitations with Dirac-like dispersions that quantitatively match theoretical predictions of Majorana bands based on the reported Kitaev interactions. Our findings in these ultraclean crystals provide strong evidence that the FIQD state of $α$-RuCl$_3$ is a robust KQSL, resilient against small disorder perturbations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_00971 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Bulk excitations in ultraclean $α$-RuCl$_3$: Quantitative evidence for Majorana dispersions in a Kitaev quantum spin liquid Imamura, Kumpei Namba, Ryuichi Ishioka, Riku Ishihara, Kota Matsuda, Yuji Lee, Seunghun Moon, Eun-Gook Hashimoto, Kenichiro Shibauchi, Takasada Strongly Correlated Electrons The spin-orbit coupled Mott insulator $α$-RuCl$_3$ has emerged as a prime candidate for realizing the Kitaev quantum spin liquid (KQSL), characterized by Majorana quasiparticles, whose edge states exhibit a distinctive half-integer quantized thermal Hall conductivity. However, its van der Waals nature makes its thermal Hall response highly sensitive to structural disorder, leading to sample-dependent variations. Here, we investigate low-energy bulk excitations in the field-induced quantum disordered (FIQD) state of newly available ultraclean single crystals of $α$-RuCl$_3$. High-resolution specific heat measurements under in-plane magnetic field rotation reveal an anisotropic excitation gap, whose field dependence is consistent with the Majorana gap in the KQSL state. Remarkably, when the field aligns with Ru-Ru bond directions, we observe gapless excitations with Dirac-like dispersions that quantitatively match theoretical predictions of Majorana bands based on the reported Kitaev interactions. Our findings in these ultraclean crystals provide strong evidence that the FIQD state of $α$-RuCl$_3$ is a robust KQSL, resilient against small disorder perturbations. |
| title | Bulk excitations in ultraclean $α$-RuCl$_3$: Quantitative evidence for Majorana dispersions in a Kitaev quantum spin liquid |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2505.00971 |