Abstract
The rich anisotropic transport behaviour shown by ferromagnetic semiconductors arises from a complex interplay of their electronic density of states and magnetic response. Such behaviour promises to enable devices whose ability to manipulate information in the form of electronic spin goes well beyond the now ubiquitous spin-valve read heads of magnetoelectronics, and on a platform that is compatible with conventional complementary metal oxide semiconductor technology. Most ferromagnetic semiconductor devices so far have relied on the bulk anisotropic behaviour of their constituent layers. Recent improvements in lithographic patterning enable the fabrication of a novel class of devices in which the anisotropy of many individual elements can be independently engineered. Here we demonstrate the first such device consisting of two nanobars with mutually orthogonal easy axes linked by a constriction. It behaves as a non-volatile memory element, where information can be written by setting the relative orientation of the magnetization of the nanobars, and read by measuring the constriction resistance.
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References
Awschalom, D. D. & Flatté, M. F. Challenges for semiconductor spintronics. Nature Phys. 3, 153–159 (2007).
Åkerman, J. Toward a universal memory. Science 308, 508–510 (2005).
Allwood, D. A. et al. Magnetic domain-wall logic. Science 309, 1688–1692 (2005).
Parkin, S. S. P. Shiftable magnetic shift register and method of using the same. US patent 6,834,005 (2004).
Baxter, D. V. et al. Anisotropic magnetoresistance in Ga1−xMnxAs. Phys. Rev. B 65, 212407 (2002).
Tang, H. X., Kawakami, R. K., Awschalom, D. D. & Roukes, M. L. Giant planar Hall effect in epitaxial (Ga,Mn)As devices. Phys. Rev. Lett. 90, 107201 (2003).
Gould, C. et al. Tunneling anisotropic magnetoresistance: A spin-valve-like tunnel magnetoresistance using a single magnetic layer. Phys. Rev. Lett. 93, 117203 (2004).
Rüster, C. et al. Very large tunneling anisotropic magnetoresistance of a (Ga,Mn)As/GaAs/(Ga,Mn)As stack. Phys. Rev. Lett. 94, 027203 (2005).
Pappert, K. et al. Magnetization-switched metal–insulator transition in a (Ga,Mn)As tunnel device. Phys. Rev. Lett. 97, 186402 (2006).
Wunderlich, J. et al. Coulomb blockade anisotropic magnetoresistance effect in a (Ga,Mn)As single-electron transistor. Phys. Rev. Lett. 97, 077201 (2006).
Hümpfner, S. et al. Lithographic engineering of anisotropies in (Ga,Mn)As. Appl. Phys. Lett. 90, 102102 (2007).
Yamanouchi, M., Chiba, D., Matsukura, F. & Ohno, H. Current-induced domain-wall switching in a ferromagnetic semiconductor structure. Nature 428, 539 (2004).
Gould, C. et al. Current assisted magnetization switching in (Ga,Mn)As nanodevices. Jpn. J. Appl. Phys. 45, 3860–3862 (2006).
Jan, J. P. in Solid State Physics (eds Seitz, F. & Turnbull, D.) (Academic, New York, 1957).
McGuire, T. R. & Potter, R. I. Anisotropic magnetoresistance in ferromagnetic 3d alloys. IEEE Trans. Magn. 11, 1018–1038 (1975).
Rushforth, A. W. et al. AMR and magnetometry studies of ultra thin GaMnAs films. Phys. Status Solidi C 3, 4078–4081 (2006).
Schmidt, M. J. et al. Bound hole states in a ferromagnetic (Ga,Mn)As environment. Preprint at <http://arxiv.org/abs/cond-mat/0704.2028> (2007).
Rüster, C. et al. Very large magnetoresistance in lateral ferromagnetic (Ga,Mn)As wires with nanoconstrictions. Phys. Rev. Lett. 91, 216602 (2003).
Bruno, P. Geometrically constrained magnetic wall. Phys. Rev. Lett. 83, 2425 (1999).
For details of the growth, see Schott, G. M. et al. Influence of growth conditions on the lattice constant and composition of (Ga,Mn)As. Appl. Phys. Lett. 82, 4678–4680 (2003).
Baca, A. G. & Ashby, C. I. H. Fabrication of GaAs Devices (IEE, London, 2005).
Matsukura, F. et al. Magnetotransport properties of metallic (Ga,Mn)As films with compressive and tensile strain. Physica E 21, 1032–1036 (2004).
Acknowledgements
The authors thank M. Sawicki and M. J. Schmidt for useful discussions and V. Hock and T. Borzenko for help in sample fabrication. We acknowledge financial support from the EU (NANOSPIN FP6-IST-015728) and the German DFG (BR1960/2-2).
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Pappert, K., Hümpfner, S., Gould, C. et al. A non-volatile-memory device on the basis of engineered anisotropies in (Ga,Mn)As. Nature Phys 3, 573–578 (2007). https://doi.org/10.1038/nphys652
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DOI: https://doi.org/10.1038/nphys652
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