TY - JOUR

T1 - Closing the gap between spatial and spin dynamics of electrons at the metal-to-insulator transition

AU - Lonnemann, J. G.

AU - Rugeramigabo, E. P.

AU - Oestreich, M.

AU - Hübner, J.

N1 - Funding information: We acknowledge the financial support by the BMBF joint research project Q.com-H (16KIS0109 and 16KIS00107) and the Deutsche Forschungsgemeinschaft (OE 177/10-1) as well as from the NTH School for Contacts in Nanosystems.

PY - 2017/7/5

Y1 - 2017/7/5

N2 - We combine extensive precision measurements of the optically detected spin dynamics and magneto-transport measurements in a contiguous set of n-doped bulk GaAs structures, in order to unambiguously unravel the intriguing but complex contributions to the spin relaxation at the metal-to-insulator transition (MIT). Just below the MIT, the interplay between hopping induced loss of spin coherence and hyperfine interaction yields a maximum spin lifetime exceeding 800 ns. At slightly higher doping concentrations, however, the spin relaxation deviates from the expected Dyakonov-Perel mechanism which is consistently explained by a reduction of the effective motional narrowing close to the MIT. The reduction is attributed to the change of the dominant momentum scattering mechanism in the metallic impurity band, where scattering by local conductivity domain boundaries due to the intrinsic random distribution of donors becomes significant. Here, we fully identify and model all intricate contributions of the relevant microscopic scattering mechanisms, which allows the complete quantitative modeling of the electron spin relaxation in the entire regime from weakly interacting up to fully delocalized electrons.

AB - We combine extensive precision measurements of the optically detected spin dynamics and magneto-transport measurements in a contiguous set of n-doped bulk GaAs structures, in order to unambiguously unravel the intriguing but complex contributions to the spin relaxation at the metal-to-insulator transition (MIT). Just below the MIT, the interplay between hopping induced loss of spin coherence and hyperfine interaction yields a maximum spin lifetime exceeding 800 ns. At slightly higher doping concentrations, however, the spin relaxation deviates from the expected Dyakonov-Perel mechanism which is consistently explained by a reduction of the effective motional narrowing close to the MIT. The reduction is attributed to the change of the dominant momentum scattering mechanism in the metallic impurity band, where scattering by local conductivity domain boundaries due to the intrinsic random distribution of donors becomes significant. Here, we fully identify and model all intricate contributions of the relevant microscopic scattering mechanisms, which allows the complete quantitative modeling of the electron spin relaxation in the entire regime from weakly interacting up to fully delocalized electrons.

UR - http://www.scopus.com/inward/record.url?scp=85026378472&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.96.045201

DO - 10.1103/PhysRevB.96.045201

M3 - Article

AN - SCOPUS:85026378472

VL - 96

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 4

M1 - 045201

ER -