TY - JOUR
T1 - Room Temperature Spin-to-Charge Conversion in Amorphous Topological Insulating Gd-Alloyed BixSe1-x/CoFeB Bilayers
AU - Sahu, Protyush
AU - Yang, Yifei
AU - Fan, Yihong
AU - Jaffrès, Henri
AU - Chen, Jun Yang
AU - Devaux, Xavier
AU - Fagot-Revurat, Yannick
AU - Migot, Sylvie
AU - Rongione, Enzo
AU - Chen, Tongxin
AU - Abel Dainone, Pambiang
AU - George, Jean Marie
AU - Dhillon, Sukhdeep
AU - Micica, Martin
AU - Lu, Yuan
AU - Wang, Jian Ping
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/8/16
Y1 - 2023/8/16
N2 - Disordered topological insulator (TI) films have gained intense interest by benefiting from both the TI’s exotic transport properties and the advantage of mass production by sputtering. Here, we report on the clear evidence of spin-charge conversion (SCC) in amorphous Gd-alloyed BixSe1-x (BSG)/CoFeB bilayers fabricated by sputtering, which could be related to the amorphous TI surface states. Two methods have been employed to study SCC in BSG (tBSG = 6-16 nm)/CoFeB(5 nm) bilayers with different BSG thicknesses. First, spin pumping is used to generate a spin current in CoFeB and detect SCC by the inverse Edelstein effect (IEE). The maximum SCC efficiency (SCE) is measured to be as large as 0.035 nm (IEE length λIEE) in a 6 nm thick BSG sample, which shows a strong decay when tBSG increases due to the increase of BSG surface roughness. The second method is THz time-domain spectroscopy, which reveals a small tBSG dependence of SCE, validating the occurrence of a pure interface state-related SCC. Furthermore, our angle-resolved photoemission spectroscopy data show dispersive two-dimensional surface states that cross the bulk gap until the Fermi level, strengthening the possibility of SCC due to the amorphous TI states. Our studies provide a new experimental direction toward the search for topological systems in amorphous solids.
AB - Disordered topological insulator (TI) films have gained intense interest by benefiting from both the TI’s exotic transport properties and the advantage of mass production by sputtering. Here, we report on the clear evidence of spin-charge conversion (SCC) in amorphous Gd-alloyed BixSe1-x (BSG)/CoFeB bilayers fabricated by sputtering, which could be related to the amorphous TI surface states. Two methods have been employed to study SCC in BSG (tBSG = 6-16 nm)/CoFeB(5 nm) bilayers with different BSG thicknesses. First, spin pumping is used to generate a spin current in CoFeB and detect SCC by the inverse Edelstein effect (IEE). The maximum SCC efficiency (SCE) is measured to be as large as 0.035 nm (IEE length λIEE) in a 6 nm thick BSG sample, which shows a strong decay when tBSG increases due to the increase of BSG surface roughness. The second method is THz time-domain spectroscopy, which reveals a small tBSG dependence of SCE, validating the occurrence of a pure interface state-related SCC. Furthermore, our angle-resolved photoemission spectroscopy data show dispersive two-dimensional surface states that cross the bulk gap until the Fermi level, strengthening the possibility of SCC due to the amorphous TI states. Our studies provide a new experimental direction toward the search for topological systems in amorphous solids.
KW - THz time-domain spectroscopy
KW - amorphous
KW - spin pumping
KW - spin-to-charge conversion
KW - topological insulator
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U2 - 10.1021/acsami.3c07695
DO - 10.1021/acsami.3c07695
M3 - Article
C2 - 37550946
AN - SCOPUS:85168221781
SN - 1944-8244
VL - 15
SP - 38592
EP - 38602
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 32
ER -