Voltage-induced ferromagnetism in a diamagnet
Voltage-induced ferromagnetism in a diamagnet
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DOI：
10.1126/sciadv.abb7721
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发表时间：
2020-07
期刊：
影响因子：
13.6
通讯作者：
Jeff Walter;Bryan Voigt;Ezra Day-Roberts;Kei Heltemes;R. Fernandes;T. Birol;C. Leighton
中科院分区：
文献类型：
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作者：
Jeff Walter;Bryan Voigt;Ezra Day-Roberts;Kei Heltemes;R. Fernandes;T. Birol;C. Leighton
离子液体门控可以在抗磁性FeS2中实现电压感应铁磁性，即在“非磁性”材料中。最近，越来越多令人印象深刻的电压控制磁性的演示已经实现，突出了低功耗数据处理和存储的潜力。磁离子方法似乎特别有前途，电解质和离子导体能够控制铁磁性和调节磁各向异性。然而，一个明显的限制是，这些器件要么电调谐已知的铁磁体，要么从另一种磁性状态（例如反铁磁性）电诱导铁磁性。在这里，我们证明了铁磁性甚至可以在反磁性（零自旋）状态下被电压诱导，这表明有用的磁相可以在“非磁性”材料中被电诱导。我们使用离子液体门控抗磁性FeS2作为模型系统，表明只要1 V就可以通过静电表面反转诱导可逆的绝缘体-金属转变。异常霍尔测量揭示了高达25k的电可调谐表面铁磁性。基于密度泛函理论的模型解释了这一点，即通过填充窄eg带引起的斯通纳铁磁性。
Ionic liquid gating is shown to enable voltage-induced ferromagnetism in diamagnetic FeS2, i.e., in a “nonmagnetic” material. Increasingly impressive demonstrations of voltage-controlled magnetism have been achieved recently, highlighting potential for low-power data processing and storage. Magnetoionic approaches appear particularly promising, electrolytes and ionic conductors being capable of on/off control of ferromagnetism and tuning of magnetic anisotropy. A clear limitation, however, is that these devices either electrically tune a known ferromagnet or electrically induce ferromagnetism from another magnetic state, e.g., antiferromagnetic. Here, we demonstrate that ferromagnetism can be voltage-induced even from a diamagnetic (zero-spin) state suggesting that useful magnetic phases could be electrically induced in “nonmagnetic” materials. We use ionic liquid–gated diamagnetic FeS2 as a model system, showing that as little as 1 V induces a reversible insulator-metal transition by electrostatic surface inversion. Anomalous Hall measurements then reveal electrically tunable surface ferromagnetism at up to 25 K. Density functional theory–based modeling explains this in terms of Stoner ferromagnetism induced via filling of a narrow eg band.