Bilateral Hydrogenation Realizes High-Temperature Quantum Anomalous Hall Insulator in 2D Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$
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| Format: | Preprint |
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2025
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| _version_ | 1866914031947743232 |
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| author | Li, Xiang Yi, Xin-Wei You, Jing-Yang Li, Jia-Wen Yang, Qing-Han Su, Gang Gu, Bo |
| author_facet | Li, Xiang Yi, Xin-Wei You, Jing-Yang Li, Jia-Wen Yang, Qing-Han Su, Gang Gu, Bo |
| contents | The pursuit of high-temperature quantum anomalous Hall (QAH) insulators faces fundamental challenges, including narrow topological gaps and low Curie temperatures ($T_{\text{C}}$) in existing materials. Here, we propose a transformative strategy using bilateral hydrogenation to engineer a robust QAH state in the topologically trivial ferromagnetic semiconductor Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$. First-principles calculations reveal that hydrogenation induces a topological phase transition in Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$ by shifting its Dirac points-originally embedded in the conduction bands-to the vicinity of the Fermi level in Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$H$_{\text{6}}$. This electronic restructuring, coupled with spin-orbit coupling, opens a global topological gap of 118.1 meV, establishing a robust QAH state with Chern number $C=$ 3. Concurrently, hydrogenation enhances ferromagnetic superexchange via the $d_{z^{2}}$-$p_{z}$-$d_{xz}$ channel, significantly strengthening the nearest-neighbor coupling $J_{\text{1}}$ by 3.06 times and switching $J_{\text{2}}$ from antiferromagnetic to ferromagnetic. Monte Carlo simulations predict a high $T_{\text{C}}$ = 198 K, sustained well above liquid nitrogen temperature and far exceeding pristine Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$ (28 K). This work establishes surface hydrogenation as a powerful route to simultaneously control topology and magnetism in 2D materials, unlocking high-temperature QAH platforms for dissipationless spintronic applications. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_09164 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Bilateral Hydrogenation Realizes High-Temperature Quantum Anomalous Hall Insulator in 2D Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$ Li, Xiang Yi, Xin-Wei You, Jing-Yang Li, Jia-Wen Yang, Qing-Han Su, Gang Gu, Bo Mesoscale and Nanoscale Physics The pursuit of high-temperature quantum anomalous Hall (QAH) insulators faces fundamental challenges, including narrow topological gaps and low Curie temperatures ($T_{\text{C}}$) in existing materials. Here, we propose a transformative strategy using bilateral hydrogenation to engineer a robust QAH state in the topologically trivial ferromagnetic semiconductor Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$. First-principles calculations reveal that hydrogenation induces a topological phase transition in Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$ by shifting its Dirac points-originally embedded in the conduction bands-to the vicinity of the Fermi level in Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$H$_{\text{6}}$. This electronic restructuring, coupled with spin-orbit coupling, opens a global topological gap of 118.1 meV, establishing a robust QAH state with Chern number $C=$ 3. Concurrently, hydrogenation enhances ferromagnetic superexchange via the $d_{z^{2}}$-$p_{z}$-$d_{xz}$ channel, significantly strengthening the nearest-neighbor coupling $J_{\text{1}}$ by 3.06 times and switching $J_{\text{2}}$ from antiferromagnetic to ferromagnetic. Monte Carlo simulations predict a high $T_{\text{C}}$ = 198 K, sustained well above liquid nitrogen temperature and far exceeding pristine Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$ (28 K). This work establishes surface hydrogenation as a powerful route to simultaneously control topology and magnetism in 2D materials, unlocking high-temperature QAH platforms for dissipationless spintronic applications. |
| title | Bilateral Hydrogenation Realizes High-Temperature Quantum Anomalous Hall Insulator in 2D Cr$_{\text{2}}$Ge$_{\text{2}}$Te$_{\text{6}}$ |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2509.09164 |