Kuroda K, Tomita T, Suzuki M-T, Bareille C, Nugroho A A, Goswami P, Ochi M, Ikhlas M, Nakayama M, Akebi S, Noguchi R, Ishii R, Inami N, Ono K, Kumigashira H, Varykhalov A, Muro T, Koretsune T, Arita R, Shin S, Kondo Takeshi, Nakatsuji S
Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan.
CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
Nat Mater. 2017 Nov;16(11):1090-1095. doi: 10.1038/nmat4987. Epub 2017 Sep 25.
Weyl fermions have been observed as three-dimensional, gapless topological excitations in weakly correlated, inversion-symmetry-breaking semimetals. However, their realization in spontaneously time-reversal-symmetry-breaking phases of strongly correlated materials has so far remained hypothetical. Here, we report experimental evidence for magnetic Weyl fermions in MnSn, a non-collinear antiferromagnet that exhibits a large anomalous Hall effect, even at room temperature. Detailed comparison between angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations reveals significant bandwidth renormalization and damping effects due to the strong correlation among Mn 3d electrons. Magnetotransport measurements provide strong evidence for the chiral anomaly of Weyl fermions-namely, the emergence of positive magnetoconductance only in the presence of parallel electric and magnetic fields. Since weak magnetic fields (approximately 10 mT) are adequate to control the distribution of Weyl points and the large fictitious fields (equivalent to approximately a few hundred T) produced by them in momentum space, our discovery lays the foundation for a new field of science and technology involving the magnetic Weyl excitations of strongly correlated electron systems such as MnSn.
外尔费米子已在弱关联、破坏空间反演对称性的半金属中被观测为三维无隙拓扑激发。然而，它们在强关联材料的自发破时间反演对称性相中是否存在，至今仍停留在理论假设阶段。在此，我们报道了在MnSn中发现磁外尔费米子的实验证据，MnSn是一种非共线反铁磁体，即便在室温下也表现出显著的反常霍尔效应。角分辨光电子能谱（ARPES）测量结果与密度泛函理论（DFT）计算结果的详细对比显示，由于Mn 3d电子间的强关联，存在显著的带宽重整化和阻尼效应。磁输运测量为外尔费米子的手征反常提供了有力证据，即仅在平行电场和磁场存在时才会出现正磁导率。鉴于弱磁场（约10 mT）足以控制外尔点的分布以及它们在动量空间中产生的大虚拟场（相当于几百特斯拉），我们的发现为涉及强关联电子体系（如MnSn）磁外尔激发的新科技领域奠定了基础。
