Abstract
We report the electronic, magnetic and transport properties of a prototypical antiferromagnetic (AFM) spintronic device. We chose Cr as the active layer because it is the only room-temperature AFM elemental metal. We sandwiched Cr between two non-magnetic metals (Pt or Au) with large spin-orbit coupling. We also inserted a buffer layer of insulating MgO to mimic the structure and finite resistivity of a real device. We found that, while spin-orbit has a negligible effect on the current flowing through the device, the MgO layer plays a crucial role. Its effect is to decouple the Cr magnetic moment from Pt (or Au) and to develop an overall spin magnetization. We have also calculated the spin-polarized ballistic conductance of the device within the Büttiker–Landauer framework, and we have found that for small applied bias our Pt/Cr/MgO/Pt device presents a spin polarization of the current amounting to ≃25%.
Highlights
In 1857 William Thompson first observed the phenomenon of magnetoresistance, which allows to significantly change the electrical resistance of a conductor by applying an external magnetic field
The research in spintronics led to the discovery of tunnel magnetoresistance (TMR) [3], where electrons propagate thank to the tunnel effect, making the phenomenon strictly quantum-mechanical
We address AFM spintronics from first principles density functional theory (DFT)
Summary
In 1857 William Thompson first observed the phenomenon of magnetoresistance, which allows to significantly change the electrical resistance of a conductor by applying an external magnetic field. The resistance of such a device is tunable by modifying the magnetic orientation of one of the two layers, for example by applying an external magnetic field This discovery opened the way to spintronics, which aims at controlling and manipulating the electron magnetic moments and the spin polarized current. The research in spintronics led to the discovery of tunnel magnetoresistance (TMR) [3], where electrons propagate thank to the tunnel effect, making the phenomenon strictly quantum-mechanical These type of devices, called Mott devices, can achieve magnetoresistance ratios (defined as the ratio between the spin-polarized current and the total current) up to 20 times higher than normal GMRs: for these reasons they are going to be further investigated as promising future memory components.
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