Speaker
Description
Topologically nontrivial magnetic orders have attracted remarkable attention since the discovery of magnetic skyrmions in MnSi [1]. The term “magnetic skyrmion” originally refers to a particle-like swirling spin object in a magnetic material. However, it often appears in a form of periodic lattice, which is regarded as a long-range magnetic order described by multiple magnetic modulation wave vectors (q-vectors), namely, a multi-q magnetic order. Neutron diffraction is one of the most powerful techniques to study the periodically modulated magnetic structures including the skyrmion lattices (SkLs). In this talk, we will introduce our neutron scattering studies on the centrosymmetric skyrmion-host materials, Gd2PdSi3[2], EuAl4 [3].
In the early studies of magnetic skyrmions, ferromagnets with non-centrosymmetric crystal structure were considered to be the most promising candidates for skyrmion-host materials since competitions between Dzyaloshinskii-Moriya (DM) and ferromagnetic interactions can induce long-period modulated magnetic structures. However, subsequent studies demonstrated that SkLs can also be realized in centrosymmetric magnets, in which long-range interactions arising from couplings between conduction electrons and localized magnetic moments play essential roles. Gd2PdSi3 is one of the centrosymmetric skyrmion hosts and exhibits a large topological Hall effect in the first-field-induced phase [4]. The magnetic structures of this system were first studied by resonant x-ray magnetic scattering [4]. We further investigated the temperature dependence of the magnetic structure by polarized neutron scattering at PONTA spectrometer in JRR-3 [2]. Another example is EuAl4, which shows a variety of magnetic orders depending on temperature and magnetic field. To identify these magnetic phases, we performed polarized neutron scattering at PONTA and TAIKAN(BL15) in Materials and Life-science experimental Facility of J-PARC, revealing two distinct SkL phases in in this compound [3].
In this talk, we also briefly introduce our recent attempt to combine the polarized neutron scattering technique with pulsed high magnetic fields.
References
[1] S. Muhlbauer et al., Science 323, 915 (2009).
[2] J. Ju et al., Phys. Rev. B 107, 024405 (2023).
[3] R. Takagi et al., Nat. Commun. 13, 1472 (2022).
[4] T. Kurumaji et al., Science 365, 914 (2019).
