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    Challenges in electrical detection of spin-orbit torque in Ir20Mn80/Pt hetero-structures
    (Ios Press, 2023) Goksal, Ilkin; Piskin, Hasan; Kocaman, Bayram; Akin, Kutay; Cay, Dogukan; Selvi, Ege; Karakas, Vedat
    Manipulation of antiferromagnetic sublattice orientations, a key challenge in spintronic device applications, requires unconventional methods such as current induced torques including Spin Transfer Torque (STT) and Spin-Orbit Torque (SOT). In order to observe the deviation of the Neel vector from the anisotropy axis, one of the simplest approaches is the electrical detection, whereby one monitors the change in resistance as a function of applied current. In this work, we have investigated the conditions under which an ultra-thin metallic antiferromagnet, Ir20Mn80 becomes susceptible to SOT effects by studying antiferromagnetic layer structure and thickness dependence in antiferromagnetic metal (Ir20Mn80)/heavy metal (Pt) superlattices. Our electrical measurements reveal that in bilayer structures there exists a shallow range of Ir20Mn80 thicknesses (similar to 1-2 nm) for which SOT driven control of spins is apparent, whereas for lower thicknesses incomplete sublattice formation and for higher thicknesses improved thermal stability prohibits vulnerability to spin currents. Furthermore, in multilayers, structural changes in Ir20Mn80 layer quenches local torques due to stronger (111) magnetocrystalline anisotropy. These results suggest that an exhaustive optimization of the antiferromagnet parameters is crucial for the successful deployment of spintronic devices.
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    Öğe
    Correlation of blocking and Néel temperatures in ultrathin metallic antiferromagnets
    (Amer Physical Soc, 2024) Akin, Kutay; Piskin, Hasan; Selvi, Ege; Demircanli, Emre; Ari, Sevval; Zadeh, Mohammad Hassan Ramezan; Kocaman, Bayram
    Nonvolatile spintronics-based devices that utilize electron spin both to store and transport information face a great challenge when scaled to nanosized dimensions due to loss of thermal stability and stray field- induced disturbance in closely packed magnetic bits. The potential replacement of ferromagnetic materials with antiferromagnets may overcome some of these issues owing to the superior robustness of sublattice spin orientations to magnetic field disturbance as long as they are kept well below the N & eacute;el temperature, which is hard to measure with conventional methods, especially in the ultrathin limit. In this work, we have employed spin pumping from a soft ferromagnetic NiFe layer into widely used ultrathin metallic antiferromagnet Ir20Mn80, 20 Mn 80 , FeMn, PtMn, PdMn, or NiMn with thicknesses in the 0.7-3 nm range, as a probe to detect damping enhancement during magnetic phase-transitions. Independent measurements of the blocking temperature with magnetometry reveal that temperature-dependent shifts in the resonance peaks can also be used to measure the blocking temperature, enabling the analysis of the correlation between the N & eacute;el and blocking temperatures in trilayers with the permalloy and antiferromagnetic layer separated by a 3-nm-thick spacer layer. The thickness-dependent characterization of thermal stability in antiferromagnets provides a key element for scalable and ultrafast antiferromagnetic spintronics.