Three-dimensional bulk Fermi surfaces and Weyl crossings of CoMnGa thin films underneath a protection layer

Kono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki; Muro, Takayuki*; Goto, Kazuki*; Sakuraba, Yuya*; Umetsu, Rie*; Kimura, Akio*

Physical Review B, 104(19), p.195112_1 - 195112_8, 2021/11

https://doi.org/10.1103/PhysRevB.104.195112

Angle-resolved photoelectron spectroscopy utilizing soft X-ray synchrotron radiation was applied to Heusler-type CoMnGa thin films that have a 1-nm Al capping layer. The bulk Fermi surfaces and band structures varied along the out-of-plane momentum, stemming from the three-dimensional crystal structure, in the absence of any in situ surface treatment. In addition, there were characteristic intersecting bands (Weyl cones), with crossing points near the Fermi level, which were consistent with computed results. The Weyl cones are of bulk origin and are responsible for the high anomalous Nernst and the anomalous Hall coefficients. A close comparison of the experimental band structures in CoMnGe and CoMnGa indicated that the rigid band picture is valid in both alloys and that fine carrier tuning is possible by replacing Ga with Ge to improve the anomalous conductivity.

Unveiling spin-dependent unoccupied electronic states of CoMnGe (Ga) film via Ge (Ga) absorption spectroscopy

Yoshikawa, Tomoki*; Antonov, V. N.*; Kono, Takashi*; Kakoki, Masaaki*; Sumida, Kazuki; Miyamoto, Koji*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; Sakuraba, Yuya*; et al.

Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08

https://doi.org/10.1103/PhysRevB.102.064428

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators SbVTe

Sumida, Kazuki*; Kakoki, Masaaki*; Reimann, J.*; Nurmamat, M.*; Goto, Shinichi*; Takeda, Yukiharu; Saito, Yuji; Kokh, K. A.*; Tereshchenko, O. E.*; Gdde, J.*; et al.

New Journal of Physics (Internet), 21(9), p.093006_1 - 093006_8, 2019/09

https://doi.org/10.1088/1367-2630/ab3ac6

Observation of spin-polarized Weyl cones and giant anomalous Nernst effect in CoMnGa films

Sumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taichi*; et al.

no journal, , 

no abstracts in English

Observation of temperature dependence of spin-polarized electronic structure in CoMnSi Heusler alloy films

Sumida, Kazuki; Kakoki, Masaaki*; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Goto, Kazuki*; Miyamoto, Koji*; Miura, Yoshio*; Hono, Kazuhiro*; Okuda, Taichi*; et al.

no journal, , 

no abstracts in English

Observation of spin-polarized Weyl cones and half-metallicity in the quaternary Heusler CoMn(Al,Si) thin films

Sumida, Kazuki; Kakoki, Masaaki*; Sakuraba, Yuya*; Kono, Takashi*; Goto, Kazuki*; Miyamoto, Koji*; Hono, Kazuhiro*; Okuda, Taichi*; Kimura, Akio*

no journal, , 

no abstracts in English