Magnetism and Topology: From Magnetic Topological Insulators to the Emerging Altermagnets

日時　2025年12月18日　（木）　14：00～15：00
場所　オンライン(Zoom形式)
講師　Mohit Mudgal
(Indian Institute of Technology Kanpur)

The study of new quantum states of matter, particularly those emerging from the interplay between nontrivial band topology and magnetism, is a major focus in condensed matter physics due to phenomena like the quantum anomalous Hall effect and axion dynamics [1]. This talk is divided into two parts. In the first part of the talk, I will discuss the magnetotransport and ARPES study of magnetic topological insulators, MnSb₈Te₁₃ and MnSb₁₂Te₁₉, part of the M_nSb_2nTe_3n+1 family, which is known for highlighting the interplay between magnetism and topology. DFT calculations predict that MnSb₈Te₁₃ behaves as an axion insulator with surface states that depend on the termination, earning it the term ‘half-magnetic topological insulator.’ However, magnetic measurements suggest that the sample exhibits weak ferromagnetism due to Mn deficiency and disorder [2]. On the other hand, MnSb₁₂Te₁₉ exhibits clear ferromagnetic behavior, with the anomalous Hall effect observed when a magnetic field is applied along the c-axis [3]. Additionally, I will discuss the non-trivial topological nature of PbBi₆Te₁₀ through ARPES and transport studies [4].

In the second part of the talk, I will explore the world of new magnetic phases, known as altermagnets. I will discuss the recent studies, challenges, and potential solutions to experimentally identifying the Altermagnets [5].

[1] Gu et. al., Nat. Comms. 12, 3524 (2021).
[2] Mudgal et. al., Phys. Rev. B. 110, 045124 (2024).
[3] Mudgal et. al., J. Phys.: Condens. Matter 36, 50LT01 (2024).
[4] Mudgal et. al., Appl. Phys. Lett. 127, 153101 (2025).
[5] Song et. al., Nat Rev Mater 10, 473–485 (2025).

問合せ先　出田真一郎（放射光科学研究所）