Low current modifications in anomalous Hall Effect signals in perpendicularly magnetized system

by Ruben Guerrero (IMDEA)

Friday, 25 May 2018 from to (Europe/Madrid)
at ALBA Synchrotron ( Marie Curie Briefing room )
Carrer de la Llum 2-26 08290 Cerdanyola del Vallès (Barcelona)


In magnetic multilayers, the interplay between the perpendicular magnetic anisotropy, the interfacial Dzyaloshinskii-Moriya interaction (DMI) and the dipolar coupling may result in the appearance of a variety of chiral magnetic textures, such as skyrmions, even at room temperature [1–3]. A strong DMI usually allows the stabilization of such topological textures which can be nucleated and manipulated via spin-orbit torque (SOT) and/or thermal effects by applying external current pulses. We have studied a Ta(5nm)/Co(0.8nm)/Pt(5nm)/Ta(5nm) trilayer deposited on SiO2 and patterned by optical lithography and Ar milling in 10 μm wide Hall bars. The interest of this structure lies in: i) the different spin Hall angle signs in Ta and Pt enhances the SOT, ii) large DMI has demonstrated in [3, 4] of the order of 1.3 mJm-2 iii) and the possibility to neglect the interlayer coupling contribution (potentially large in systems with several repetition) that may be play a fundamental role on the effect of SOT on the magnetic behavior. . We have investigated the anomalous Hall effect (AHE) that is, generally, proportional to the out of plane component of the magnetization, as function of the magnetic field applied along the z direction. We have disclosed the effect of the SOT by detecting simultaneously the Hall resistance curve and the polar Kerr hysteresis as described in reference [5]. The results exhibit a clear discrepancy at current densities as low as 6x108 Am-2 between the AHE the magnetoptical results. The difference between both curves consisted on large peaks corresponding to the annihilation and creation of magnetic domains. We have moreover investigated these features as function as the current density and in-plane magnetic fields in order to discriminate the role of the antidamping and field like torques.