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- ItemRobust metastable skyrmions with tunable size in the chiral magnet FePtMo3 N(Woodbury, NY : Inst., 2020) Sukhanov, A.S.; Heinemann, A.; Kautzsch, L.; Bocarsly, J.D.; Wilson, S.D.; Felser, C.; Inosov, D.S.The synthesis of new materials that can host magnetic skyrmions and their thorough experimental and theoretical characterization are essential for future technological applications. The β-Mn-type compound FePtMo3N is one such novel material that belongs to the chiral space group P4132, where the antisymmetric Dzyaloshinskii-Moriya interaction is allowed due to the absence of inversion symmetry. We report the results of small-angle neutron scattering (SANS) measurements of FePtMo3N and demonstrate that its magnetic ground state is a long-period spin helix with a Curie temperature of 222 K. The magnetic field-induced redistribution of the SANS intensity showed that the helical structure transforms to a lattice of skyrmions at ∼13 mT at temperatures just below TC. Our key observation is that the skyrmion state in FePtMo3N is robust against field cooling down to the lowest temperatures. Moreover, once the metastable state is prepared by field cooling, the skyrmion lattice exists even in zero field. Furthermore, we show that the skyrmion size in FePtMo3N exhibits high sensitivity to the sample temperature and can be continuously tuned between 120 and 210 nm. This offers different prospects in the control of topological properties of chiral magnets. © 2020 authors. Published by the American Physical Society.
- ItemField-Angle-Resolved Magnetic Excitations as a Probe of Hidden-Order Symmetry in CeB6(College Park, Md. : APS, 2020) Portnichenko, P.Y.; Akbari, A.; Nikitin, S.E.; Cameron, A.S.; Dukhnenko, A.V.; Filipov, V.B.; Shitsevalova, N.Yu.; Čermák, P.; Radelytskyi, I.; Schneidewind, A.; Ollivier, J.; Podlesnyak, A.; Huesges, Z.; Xu, J.; Ivanov, A.; Sidis, Y.; Petit, S.; Mignot, J.-M.; Thalmeier, P.; Inosov, D.S.In contrast to magnetic order formed by electrons' dipolar moments, ordering phenomena associated with higher-order multipoles (quadrupoles, octupoles, etc.) are more difficult to characterize because of the limited choice of experimental probes that can distinguish different multipolar moments. The heavy-fermion compound CeB6 and its La-diluted alloys are among the best-studied realizations of the long-range-ordered multipolar phases, often referred to as "hidden order."Previously, the hidden order in phase II was identified as primary antiferroquadrupolar and field-induced octupolar order. Here, we present a combined experimental and theoretical investigation of collective excitations in phase II of CeB6. Inelastic neutron scattering (INS) in fields up to 16.5 T reveals a new high-energy mode above 14 T in addition to the low-energy magnetic excitations. The experimental dependence of their energy on the magnitude and angle of the applied magnetic field is compared to the results of a multipolar interaction model. The magnetic excitation spectrum in a rotating field is calculated within a localized approach using the pseudospin representation for the Γ8 states. We show that the rotating-field technique at fixed momentum can complement conventional INS measurements of the dispersion at a constant field and holds great promise for identifying the symmetry of multipolar order parameters and the details of intermultipolar interactions that stabilize hidden-order phases. © 2020 authors. Published by the American Physical Society.