Publications (2)7.51 Total impact

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    ABSTRACT: We observe low-field hysteretic magnetoresistance in a (Ga,Mn)As single-electron transistor which can exceed 3 orders of magnitude. The sign and size of the magnetoresistance signal are controlled by the gate voltage. Experimental data are interpreted in terms of electrochemical shifts associated with magnetization rotations. This Coulomb blockade anisotropic magnetoresistance is distinct from previously observed anisotropic magnetoresistance effects as it occurs when the anisotropy in a band structure derived parameter is comparable to an independent scale, the single-electron charging energy. Effective kinetic-exchange model calculations in (Ga,Mn)As show chemical potential anisotropies consistent with experiment and ab initio calculations in transition metal systems suggest that this generic effect persists to high temperatures in metal ferromagnets with strong spin-orbit coupling.
    No preview · Article · Sep 2006 · Physical Review Letters
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    ABSTRACT: Single-electronics and spintronics are among the most intensively investigated potential complements or alternatives to CMOS electronics. Single-electronics, which is based on the discrete charge of the electron, is the ultimate in miniaturization and electro-sensitivity. Spintronics, which is based on manipulating electron spins,delivers high magneto-sensitivity and non-volatile memory effects. So far, major developments in the two fields have followed independent paths with only a few experimental studies of hybrid single-electronic/spintronic devices. Intriguing new effects have been discovered in such devices but these have not, until now, offered the possibility of useful new functionalities. Here we demonstrate a device which shows a new physical effect, Coulomb blockade anisotropic magnetoresistance, and which offers a route to non-volatile, low-field, and highly electro- and magneto-sensitive operation. Since this new phenomenon reflects the magnetization orientation dependence of the classical single-electron charging energy it does not impose constraints on the operational temperature associated with more subtle quantum effects, such as resonant or spin-coherent tunneling.
    Full-text · Article · Mar 2006