Oral Session B1 (Wednesday, February 14)
Chair: Kyung-Jin Lee, KAIST

Keynote Talk
9: 00 - 9 : 40

Shunsuke Fukami
Research Institute of Electrical Communication, Tohoku University

Electrical control of noncollinear
antiferromagnetic Mn3Sn
Dynamics of collective spin structures induced by various electrical means has been of paramountinterest in magnetics and spintronics fields, and many interesting phenomena have been revealed,leading to various opportunities of applications. Non-collinear antiferromagnet with chiral-spin
structure is an attractive system showing intriguing properties that were believed to be inherent toferromagnets such as the anomalous Hall eﬀect [1]. Here I discuss physics and functionalities ofMn3Sn, a representative room-temperature noncollinear antiferromagnetic system. First, I willshow an epitaxial thin-film growth technique that is necessary to explore the device functionalities[2] and show basic magneto-transport properties [2,3]. Then, I will show the characteristic
response of the chiral-spin structure of Mn3Sn epitaxial heterostructures under a spin-orbit torquegenerated by an electric current [4]. If time allows, I will also present our studies on the domain
structure [6] and thermal stability [7] of Mn3Sn thin film and nanodot.
This work is performed under a collaboration with Y. Takeuchi, J.-Y. Yoon, T. Uchimura, Y. Sato,Y. Yamane, J. Han, S. Kanai, J. Ieda, and H. Ohno. This study is partly supported by JSPS
Kakenhi 19H05622, MEXT X-NICS JPJ011438, and RIEC Cooperative Research Projects.
References[1] S. Nakatsuji et al., Nature 527, 212 (2015).
[2] J.-Y. Yoon et al., Appl. Phys. Express 13, 013001 (2019)[3] J.-Y. Yoon et al. AIP Adv. 11, 065318 (2021).
[4] Y. Takeuchi et al., Nature Materials 20, 1364 (2021).
[5] J.-Y. Yoon et al., Nature Materials 22, 1106 (2023).
[6] T. Uchimura et al., Appl. Phys. Lett. 120, 172405 (2022).
[7] Y. Sato et al., Appl. Phys. Lett. 122, 122404 (2023).

Oral Session B1 (Wednesday, February 14)
Chair: Kyung-Jin Lee, KAIST

Contributed Oral
9: 40 - 10 : 00

Electrical manipulation and detection of topologicalantiferromagnetic state in Mn3Sn-based epitaxial
heterostructures
T. Higo1,2, K. Kondou3, T. Nomoto4, X. Chen1,5, K. Tanaka1, M. Shiga1,6, S.
Sakamoto2, H. Tsai1, H. Idzuchi1,2, H. Kosaki2, T. Matsuo1,8, D. Nishio-Hamane2, R.
Arita3,4, Y. Otani2,3,7, S. Miwa2,7, S. Nakatsuji1,2,7,8
1. Dept. of Physics, The University of Tokyo, Japan
2. Institute for Solid State Physics, The University of Tokyo, Japan
3. Center for Emergent Matter Science, RIKEN, Japan
4. Research Center for Advanced Science and Technology, The University of Tokyo, Japan
5. Lawrence Berkeley National Laboratory, University of California, USA
6. Dept. of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Japan
7. Trans-scale Quantum Science Institute, The University of Tokyo, Japan
8. IQM, Department of Physics and Astronomy, Johns Hopkins University, USA
Antiferromagnetic materials have garnered significant attention for their favorable properties in device applications,
including negligible stray/demagnetizing fields and ultrafast spin dynamics [1]. The non-collinear antiferromagnet(AFM) Mn3Sn [2], a prominent example of time-reversal symmetry-breaking AFMs, is a magnetic Weyl
semimetal with unique AF ordering hosting cluster magnetic octupoles, leading to large transverse responses [2,3].
The research targets are shifting fundamental studies using bulk samples to exploring spintronic properties using
thin films. This presentation focuses on our recent studies involving heterointerfaces based on Mn3Sn. We havesuccessfully manipulated the chiral AF order in bilayer films composed of polycrystalline Mn3Sn and heavy metals,
demonstrating the potential for spin-orbit torque (SOT) [4]. This research extends to heterostructures comprising
epitaxial Mn3Sn and heavy metals [5,6], where we have achieved SOT-induced perpendicular magnetic recording
for the first time in AFMs [6], leveraging high-quality Mn3Sn layers fabricated by MBE methods. These samples
exhibit large Hall conductivity of ~40 Ω-1cm-1 comparable to that obtained in the bulk single crystals, and thefabrication of Mn3Sn/MgO/Mn3Sn stacks has also enabled the observation of the tunnel magnetoresistance eﬀect
at room temperature [7]. These results oﬀer promising avenues for the development of AF spintronics.

References[1] T. Jungwirth et al., Nat. Nano. 11, 231 (2016); V. Baltz et al., RMP 90, 015005 (2018).
[2] S. Nakatsuji, N. Kiyohara, and T. Higo, Nature 527, 212 (2015);
S. Nakatsuji and R. Arita, Annu. Rev. Condens. Matter. Phys. 13, 119 (2022).
[3] K. Kuroda, T. Tomita et al., Nat. Mater. 16, 1090 (2017).
[4] H. Tsai, T. Higo et al., Nature 580, 608 (2020).
[5] Y. Takeuchi et al., Nat. Mater. 20, 1364 (2021).
[6] T. Higo, K. Kondou et al., Nature 607, 474 (2022).
[7] X. Chen, T. Higo, K. Tanaka et al., Nature 613, 490 (2023).Oral Session B1 (Wednesday, February 14)
Chair: Kyung-Jin Lee, KAIST

Keynote Talk
10: 00 - 10 : 40

Stuart Parkin
Max Planck Institute of Microstructure Physics

The Josephson diode eﬀectWe discuss a non-reciprocal Josephson diode eﬀect in Josephson junctions, both lateral andvertical, formed from superconducting electrodes (Nb, NbSe2) separated by several 2D van der
Waals metals, NiTe2 [1] , WTe2 [2] , and PtTe2 [3] , as well as platinum that is magneticallyproximitized via a magnetic insulator [4] . Each of these materials becomes superconducting by
proximity to the conventional superconducting electrodes. The superconductivity can be sustained
over long distances of, in some cases, up to ~1 micron. The critical supercurrent densities for
current flowing in opposite directions are distinct and can vary by up to 40% or more. For the vander Waals metals the non-reciprocity is only observed in the presence of a small magnetic fieldoriented perpendicular to the supercurrent, whereas for the Pt based junctions the diode eﬀect isobserved in zero field. For vertical Josephson junctions formed from WTe2 we show that the nonreciprocity depends on the orientation of the magnetic field with respect to the crystal structure of
the WTe2, thereby proving the intrinsic origin of the Josephson diode eﬀect. Such an eﬀect could
have important applications as a novel magnetic field detector at cryogenic temperatures, forexample, to “read” magnetic domain walls in a cryogenic racetrack memory.
References

1. Pal, B. et al. Josephson diode eﬀect from Cooper pair momentum in a topological semimetal. Nat.
Phys. 18, 1228-1233 (2022).
2. Kim, J.-K. et al. Intrinsic supercurrent non-reciprocity coupled to the crystal structure of a van der Waals
Josephson barrier. Nat. Commun. accepted (2024).
3. Sivakumar, P. K. et al. Long-range Phase Coherence and Second Order ɸ_0-Josephson Eﬀect in a
Dirac Semimetal 1T-PtTe2 submitted (2024).
4. Jeon, K.-R. et al. Zero-field polarity-reversible Josephson supercurrent diodes enabled by aproximity-magnetized Pt barrier. Nat. Mater. 21, 1008-1013 (2022).