Abstract:A study of exchange bias in IrMn/Co systems is presented. Temperature and thickness dependence studies have revealed nonmonotonic behavior in both exchange bias fiel and coercivity with both variables. In particular the exchange bias fiel shows a peak for low IrMn thicknesses that is suppressed at temperatures higher than about 200 K. Calculations using the domain state model of exchange biasing are able to describe all the features seen in the experimental data.
“…The rotational anisotropy and coercivity are the largest for the sample with 3-nm IrMn. Similar thickness dependence has been observed experimentally using different techniques [37,38]. One can see a correlation between the size of the exchange bias and h z by comparing Figs.…”
Section: Origins Of the Effectsupporting
confidence: 58%
“…Inplane magnetic field of 200 Oe was applied during growth. The polycrystalline IrMn is believed to be 111 textured for the structures to exhibit such large exchange bias at room temperature [37].…”
We demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. In our study, we use an electrical detection technique of the ferromagnetic resonance driven by an in-plane ac current in a NiFe/IrMn bilayer. At room temperature, we observe antidampinglike spin torque acting on the NiFe ferromagnet, generated by an in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to the strong spin-orbit coupling, the antiferromagnetic order in IrMn governs the observed phenomenon.
“…The rotational anisotropy and coercivity are the largest for the sample with 3-nm IrMn. Similar thickness dependence has been observed experimentally using different techniques [37,38]. One can see a correlation between the size of the exchange bias and h z by comparing Figs.…”
Section: Origins Of the Effectsupporting
confidence: 58%
“…Inplane magnetic field of 200 Oe was applied during growth. The polycrystalline IrMn is believed to be 111 textured for the structures to exhibit such large exchange bias at room temperature [37].…”
We demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. In our study, we use an electrical detection technique of the ferromagnetic resonance driven by an in-plane ac current in a NiFe/IrMn bilayer. At room temperature, we observe antidampinglike spin torque acting on the NiFe ferromagnet, generated by an in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to the strong spin-orbit coupling, the antiferromagnetic order in IrMn governs the observed phenomenon.
“…In order to induce the exchange bias without field cooling, two permanent magnets were mounted below the sample holder to provide a static in-plane magnetic field of â1 kOe on the substrate surface during the whole deposition 167 . This field is able to induce the magnetic order in the growing IrMn layer at room temperature, provided that it is deposited directly onto an already existing ferromagnetic layer 168 .…”
Abstract:In this work, stretchable magnetic sensorics is successfully established by combining metallic thin films revealing a giant magnetoresistance effect with elastomeric materials. Stretchability of the magnetic nanomembranes is achieved by specific morphologic features (e.g. wrinkles), which accommodate the applied tensile deformation while maintaining the electrical and magnetic integrity of the sensor device. The entire development, from the demonstration of the world-wide first elastically stretchable magnetic sensor to the realization of a technology platform for robust, ready-touse elastic magnetoelectronics with fully strain invariant properties, is described. The prepared soft giant magnetoresistive devices exhibit the same sensing performance as on conventional rigid supports, but can be stretched uniaxially or biaxially reaching strains of up to 270% and endure over 1,000 stretching cycles without fatigue. The comprehensive magnetoelectrical characterization upon tensile deformation is correlated with in-depth structural investigations of the sensor morphology transitions during stretching.With their unique mechanical properties, the elastic magnetoresistive sensor elements readily conform to ubiquitous objects of arbitrary shapes including the human skin. This feature leads electronic skin systems beyond imitating the characteristics of its natural archetype and extends their cognition to static and dynamic magnetic fields that by no means can be perceived by human beings naturally.Various application fields of stretchable magnetoelectronics are proposed and realized throughout this work. The developed sensor platform can equip soft electronic systems with navigation, orientation, motion tracking and touchless control capabilities. A variety of novel technologies, like smart textiles, soft robotics and actuators, active medical implants and soft consumer electronics will benefit from these new magnetic functionalities.
Michael Melzer: Stretchable MagnetoelectronicsOutline 4
“…in Co/IrMn. [10][11][12] EB also exists in soft/hard FM/FM systems, where two types of EB have been reported, i.e. minor loop effect and standard EB effect.…”
Abstract:Amorphous TbFeCo thin films sputter deposited at room temperature on thermally oxidized Si substrate are found to exhibit strong perpendicular magnetic anisotropy (PMA). Atom probe tomography (APT), scanning transmission electron microscopy (STEM), and energy dispersive spectroscopy (EDS) mapping have revealed two nanoscale amorphous phases with different Tb atomic percentages distributed within the amorphous film. Exchange bias accompanied by bistable magneto-resistance states has been uncovered near room temperature by magnetization and magneto-transport measurements. The exchange anisotropy originates from the exchange interaction between the ferrimagnetic and ferromagnetic components corresponding to the two amorphous phases. This study provides a platform for exchange bias and magneto-resistance switching using single-layer amorphous ferrimagnetic thin films that require no epitaxial growth. a
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