講演情報
[20p-C501-6]Observation of high-mobility quantum transport and topological band structure
of α-Sn / Fe heterostructures
〇Soichiro Fukuoka1, Tomoki Hotta1, Le Duc Anh1,2,3, Takahiro Chiba4, Yohei Kota5, Masaaki Tanaka1,3 (1.EEIS, Univ. of Tokyo, 2.PRESTO, JST, 3.CSRN, Univ. of Tokyo, 4.FRIS, Tohoku Univ., 5.NIT, Fukushima Coll.)
キーワード：
topological Dirac semimetal、Shubnikov-de Haas oscillation、topological surface state
Among topological materials, α-Sn attracts considerable attention because it is the only single-element material exhibiting multiple topological phases. For spintronics applications, interfacing an α-Sn thin film with a ferromagnet. However, it remains unexplored how the topological band structure of α-Sn changes under the magnetic proximity effect from a ferromagnet.
In this study, we investigate the topological band structure of α-Sn thin film/Fe bilayers using quantum transport measurements and first-principles calculations. We grew a heterostructure consisting of Fe/α-Sn/InSb using molecular beam epitaxy and measured electrical transport. Strong Shubnikov–de Haas oscillations were observed. Fourier transformation revealed two frequency components, a peak Flow at 12.3 T and a peak Fhigh at 33.4 T. We obtained a Berry phase γlow = 0.28 and a mobility µlow = 28,900 cm2/Vs for the Flow component, and γhigh = 0.42, µhigh = 1,040 cm2/Vs for the Fhigh by fitting based on the Lifshitz-Kosevich theory. Because the Flow component has a topologically nontrivial Berry phase and a high mobility, we attribute this to the topological surface state (TSS) of α-Sn. On the other hand, this high-mobility TSS is absent in a 3 nm-thick non-magnetic α-Sn reference sample, where there is no Fe layer. Our finding that the magnetic proximity effect from an Fe layer induces a robust high-mobility TSS in α-Sn is surprising. The present α-Sn/Fe heterostructures provide a promising material platform for spintronic devices.
In this study, we investigate the topological band structure of α-Sn thin film/Fe bilayers using quantum transport measurements and first-principles calculations. We grew a heterostructure consisting of Fe/α-Sn/InSb using molecular beam epitaxy and measured electrical transport. Strong Shubnikov–de Haas oscillations were observed. Fourier transformation revealed two frequency components, a peak Flow at 12.3 T and a peak Fhigh at 33.4 T. We obtained a Berry phase γlow = 0.28 and a mobility µlow = 28,900 cm2/Vs for the Flow component, and γhigh = 0.42, µhigh = 1,040 cm2/Vs for the Fhigh by fitting based on the Lifshitz-Kosevich theory. Because the Flow component has a topologically nontrivial Berry phase and a high mobility, we attribute this to the topological surface state (TSS) of α-Sn. On the other hand, this high-mobility TSS is absent in a 3 nm-thick non-magnetic α-Sn reference sample, where there is no Fe layer. Our finding that the magnetic proximity effect from an Fe layer induces a robust high-mobility TSS in α-Sn is surprising. The present α-Sn/Fe heterostructures provide a promising material platform for spintronic devices.