Curved graphene: A possible answer to the problem of graphene's diverging magnetic susceptibility,Physical Review B

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Curved graphene: A possible answer to the problem of graphene's diverging magnetic susceptibility
Physical Review B ( IF 3.2 ) Pub Date : 2024-07-17 , DOI: 10.1103/physrevb.110.035421
Abdiel de Jesús Espinosa-Champo _{1,

2} , Gerardo G. Naumis ₃ , Pavel Castro-Villarreal ₂

Affiliation

A study of curved graphene in the presence and absence of a real magnetic field is conducted to determine the magnetization and magnetic susceptibility. Utilizing a Dirac model, the Landau-level energy corrections are found. These results are compared with those obtained from a tight-binding model analysis, showing good agreement with the Dirac model. The obtained spectra are then used to calculate the free energy, magnetization, and magnetic susceptibility as functions of the external magnetic field and curvature. The resulting de Haas–van Alphen effect exhibits distinctive signatures due to the curvature of graphene, including a resonance effect when the pseudomagnetic and the real magnetic fields are equal. Considering that curvature induces effective pseudomagnetic fields, a mechanical effect stemming from an electronic contribution is found, resulting in a pseudo de Haas–van Alphen effect without needing an external magnetic field. This effect is associated with oscillating (electronic) forces opposing deformations. These forces, divergent in flat graphene, suggest that graphene (without a substrate) attains mechanical equilibrium through local corrugations. These mechanical deformations prevent the theoretically calculated pristine graphene's diamagnetic divergence at low temperatures, indicating that corrugations produce a finite, experimentally measurable magnetic susceptibility. The divergent susceptibility becomes apparent only when such corrugations are removed using various strategies.

中文翻译：

弯曲石墨烯：石墨烯磁化率发散问题的可能答案

在存在和不存在真实磁场的情况下对弯曲石墨烯进行研究，以确定磁化强度和磁化率。利用狄拉克模型，找到了朗道级能量修正。这些结果与紧束缚模型分析获得的结果进行了比较，显示出与狄拉克模型的良好一致性。然后使用获得的光谱来计算作为外部磁场和曲率函数的自由能、磁化强度和磁化率。由于石墨烯的曲率，由此产生的德哈斯-范阿尔芬效应表现出独特的特征，包括当赝磁场和真实磁场相等时的共振效应。考虑到曲率会产生有效的赝磁场，我们发现了由电子贡献产生的机械效应，从而在不需要外部磁场的情况下产生伪德哈斯-范阿尔芬效应。这种效应与抵抗变形的振荡（电子）力有关。这些力在平面石墨烯中不同，表明石墨烯（没有基材）通过局部波纹达到机械平衡。这些机械变形阻止了理论上计算的原始石墨烯在低温下的抗磁发散，表明波纹产生有限的、可通过实验测量的磁化率。仅当使用各种策略去除此类波纹时，不同的敏感性才会变得明显。

更新日期：2024-07-19

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