ASCENT Theme 2(A) /Spin-orbit torque generated by amorphous FexSi1-x


Location: webex

Title: Spin-orbit torque generated by amorphous FexSi1-x

PresenterJason Hsu (Cheng-Hsiang)
PhD Student - Prof. Sayeef Salahuddin group
EECS Department - University of California, Berkeley

Abstract:  While tremendous work has gone into spin-orbit torque and spin current generation, charge-to-spin conversion efficiency remains weak in silicon to date, generally stemming from the low spin-orbit coupling (low atomic number, Z) and lack of bulk lattice inversion symmetry breaking. Here we report the observation of spin-orbit torque in an amorphous, non-ferromagnetic FexSi1-x/cobalt bilayer at room temperature, using spin torque ferromagnetic resonance and harmonic Hall measurements. Both techniques provide a minimum spin Hall angle of about 3 %, comparable to prototypical heavy metals such as Ta or Pt. According to the conventional theory of the spin Hall effect, a spin current in an amorphous material is not expected to have any substantial contribution from the electronic bandstructure. This, combined with the fact that FexSi1-x does not contain any high-Z element, paves a new avenue for understanding the underlying physics of spin-orbit interaction and opens up a new class of material systems - silicides - that is directly compatible with complementary metal-oxide-semiconductor (CMOS) processes for integrated spintronics applications. 

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