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Browsing by Author "Santos, M. B."

Now showing 1 - 3 of 3
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    Spectroscopy of Rashba spin splitting in InSb quantum wells
    Khodaparast, Giti A.; Doezema, R. E.; Chung, S. J.; Goldammer, K. J.; Santos, M. B. (American Physical Society, 2004-10-22)
    We use electron spin resonance in the far infrared to probe the Landau-level spin splitting in symmetric and asymmetric InSb quantum wells. The asymmetric wells exhibit a strong deviation in behavior from the symmetric wells at low magnetic fields with apparent g factors far in excess of the bulk g factor of InSb. These asymmetry-induced shifts in the spin resonance depend on Landau-level index as predicted by the Bychkov-Rashba model. We analyze the shifts to extract values for the Rashba parameter.
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    Spin and phase coherence lengths in n-InSb quasi-one-dimensional wires
    Kallaher, R. L.; Heremans, Jean J.; Goel, N.; Chung, S. J.; Santos, M. B. (American Physical Society, 2010-01-15)
    We present measurements of the magnetoconductance of quasi-one-dimensional wires fabricated on a two-dimensional electron system in an InSb/InAlSb heterostructure. The width and temperature dependence of the spin and phase coherence lengths in the narrow wires are examined by analyzing the magnetoconductance in antilocalization theory, modified to account for ballistic transport. The experiments indicate that the confined geometry can enhance spin coherence lengths in systems not in the motional narrowing regime and in the presence of strong cubic Dresselhaus spin-orbit interaction. Experimentally, the spin coherence lengths are found to be inversely proportional to wire width and to display a weak temperature dependence. For all wire widths the phase coherence length, after correction for finite length effects, shows a temperature dependence indicative of phase decoherence via the one-dimensional Nyquist mechanism.
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    Spin-orbit interaction determined by antilocalization in an InSb quantum well
    Kallaher, R. L.; Heremans, Jean J.; Goel, N.; Chung, S. J.; Santos, M. B. (American Physical Society, 2010-02-02)
    The magnetoresistance at temperatures below 20 K in an n-InSb/In(0.85)Al(0.15)Sb two-dimensional electron system is studied and described in terms of antilocalization due to quantum interference under strong spin-orbit interaction. The spin-orbit interaction coefficients are extracted by fitting the magnetoresistance data to an antilocalization theory distinguishing the Rashba and Dresselhaus contributions. A good agreement between magnetoresistance data and theory suggests a Rashba coefficient vertical bar alpha vertical bar approximate to 0.03 eV angstrom and a Dresselhaus coefficient gamma approximate to 490 eV angstrom(3). A strong contribution from the Dresselhaus term leads to pronounced anisotropy in the energy splitting induced by spin-orbit interaction in the two-dimensional electron dispersion.