Gate-Tunable Magnetism and Giant Magnetoresistance in Suspended Rhombohedral-Stacked Few-Layer Graphene,Nano Letters

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Gate-Tunable Magnetism and Giant Magnetoresistance in Suspended Rhombohedral-Stacked Few-Layer Graphene
Nano Letters ( IF 9.6 ) Pub Date : 2022-06-17 , DOI: 10.1021/acs.nanolett.2c00466
Yongjin Lee _{1,

2,

3} , Shi Che ₄ , Jairo Velasco ₅ , Xueshi Gao ₄ , Yanmeng Shi ₂ , David Tran ₂ , Jacopo Baima ₆ , Francesco Mauri ₇ , Matteo Calandra _{6,

8,

9} , Marc Bockrath ₄ , Chun Ning Lau ₄

Affiliation

Conventionally, magnetism arises from the strong exchange interaction among the magnetic moments of d- or f-shell electrons. It can also emerge in perfect lattices from nonmagnetic elements, such as that exemplified by the Stoner criterion. Here we report tunable magnetism in suspended rhombohedral-stacked few-layer graphene (r-FLG) devices with flat bands. At small doping levels (n ∼ 10¹¹ cm^–2), we observe prominent conductance hysteresis and giant magnetoconductance that exceeds 1000% as a function of magnetic fields. Both phenomena are tunable by density and temperature and disappear at n > 10¹² cm^–2 or T > 5 K. These results are confirmed by first-principles calculations, which indicate the formation of a half-metallic state in doped r-FLG, in which the magnetization is tunable by electric field. Our combined experimental and theoretical work demonstrate that magnetism and spin polarization, arising from the strong electronic interactions in flat bands, emerge in a system composed entirely of carbon atoms.

中文翻译：

悬浮菱面体堆叠少层石墨烯中的栅极可调磁性和巨磁阻

传统上，磁性源于 d 或 f 壳电子的磁矩之间的强交换相互作用。它也可以在非磁性元素的完美晶格中出现，例如以斯通纳准则为例。在这里，我们报告了具有扁平带的悬浮菱面体堆叠的几层石墨烯（r-FLG）器件中的可调磁性。在小掺杂水平 ( n ∼ 10 ¹¹ cm ^–2 ) 下，我们观察到显着的电导滞后和超过 1000% 的巨磁导作为磁场的函数。这两种现象都可以通过密度和温度进行调节，并在n > 10 ¹² cm ^–2或T时消失> 5 K。这些结果通过第一性原理计算得到证实，这表明在掺杂的 r-FLG 中形成了半金属态，其中磁化强度可通过电场调节。我们的综合实验和理论工作表明，由平带中的强电子相互作用引起的磁性和自旋极化出现在完全由碳原子组成的系统中。

更新日期：2022-06-17

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