Anomalous Hall effect is studied in Co/Ni multilayers with perpendicular magnetic anisotropy, which consists of ferromagnetic-ferromagnetic interfaces. The anomalous Hall coefficient of [Co/Ni]N multilayer increases with temperature. The anomalous Hall coefficient at the zero temperature limit is in the order of 0.01 μΩ cm/T and decreases with increasing the repetition N. It suggests that the Co-Ni interfacial contribution to anomalous Hall coefficient is of opposite sign to the bulk contribution. The anomalous Hall coefficient increases linearly with the resistivity of the Co/Ni multilayer, indicating the scattering may play a dominant role on the anomalous Hall effect.

We have investigated thermally activated magnetization reversal influenced by the current in a Co/Pt thin film with perpendicular magnetic anisotropy at room temperature by measuring the extraordinary Hall effect. The magnetization could reverse in a fixed magnetic field lower than the coercive field as increasing the current, which depends on the current-sweep rate. The characteristic current for zero net magnetization is small for a low current-sweep rate and a high fixed field. Magnetization reversal becomes fast for a high current-sweep rate and a high fixed field. With the constant current, the magnetization reversal is fast for a large current and a high fixed field. The magnitude of the propagation field HP∗ reduces more than 70 Oe when the current density J reaches 1.25×105 A/cm2, which is mainly on account of the sample temperature rise due to current-induced Joule heating. Also, the effective field HI associated with spin transfer and momentum transfer perhaps has a contribution to magnetization reversal through thermal activation in a multidomain macroscopic thin film. The results show that the Joule heating and current associated effective field can reduce the activation energy barriers and speed up magnetization reversal besides the applied magnetic field.

The distributions of magnetization orientation for both Landau and diamond domain structures in nano-rectangles have been investigated by micromagnetic simulation with various exchange coefficient and anisotropy constant. Both symmetric and asymmetric magnetization splitting are found in diamond domain structure, as well as only symmetric magnetization splitting in Landau structure. In the Landau structure, the splitting angle increases with the exchange coefficient but decreases slightly with the anisotropy constant, suggesting that the exchange interaction mainly contributes to the magnetization splitting in Landau structure. However in the diamond structure, the splitting angle increases with the anisotropy constant but derceases with the exchange coefficient, indicating that the magnetization splitting in diamond structure is resulted from magnetic anisotropy.

The skyrmionic state is an exciting realm of study and the skyrmions are being explored as the promising candidates of information carriers. In most systems, the skyrmions originate from the Dzyaloshinsky–Moriya interaction (DMI). However, in this work, it is demonstrated that in the triple-layer CoPt/Co/CoPt structure, the skyrmion-like state can be formed not only in the CoPt layers but also in the middle Co layer, without DMI. In this new structure, the skyrmion-like state in Co layer can exist in a large CoPt thickness range with thick Co. It can be very stable even against the external field from −500 to 200 mT along Z axis. The skyrmion number (S) in Co (SCo) can be as large as 0.9. These advanced properties make it high application potential for the future information-processing and storage devices.