A non-volatile-memory device on the basis of engineered anisotropies in (Ga,Mn)As

Abstract

Progress in (Ga,Mn)As lithography has recently allowed us to realize structures where unique magnetic anisotropy properties can be imposed locally in various regions of a given device. We make use of this technology to fabricate a device in which we study transport through a constriction separating two regions whose magnetization direction differs by 90• . We find that the resistance of the constriction depends on the flow of the magnetic field lines in the constriction region and demonstrate that such a structure constitutes a non-volatile memory device.

Strain control of magnetic anisotropy in (Ga,Mn)As microbars

“…6,7 Recently, a local control of the magnetocrystalline anisotropy has been reported, which provides the possibility for realizing non-uniform magnetization profiles and which can be utilized, e.g., in studies of current induced magnetization dynamics phenomena or non-volatile memory devices. 8,9 In these studies an efficient method of local strain control has been used which is based on lithographic patterning that allows for the relaxation of the lattice mismatch between the (Ga,Mn)As epilayer and the GaAs substrate. [8][9][10][11][12] The modification to the strain distribution can cause strong changes of the magnetic anisotropy for strains as small as 10 −4 .…”

“…8,9 In these studies an efficient method of local strain control has been used which is based on lithographic patterning that allows for the relaxation of the lattice mismatch between the (Ga,Mn)As epilayer and the GaAs substrate. [8][9][10][11][12] The modification to the strain distribution can cause strong changes of the magnetic anisotropy for strains as small as 10 −4 . The high efficiency and practical utility of the lithographic pattering control of magnetic anisotropy in (Ga,Mn)As, demonstrated in the previous works, have motivated our thorough investigation of the phenomenon which is presented in this paper.…”

Magnitude and sign control of lithography-induced uniaxial anisotropy in ultra-thin (Ga,Mn)As wires

“…4 Lithography-induced uniaxial anisotropy due to the magnetostriction effect has been observed in relatively thick ͑Ga,Mn͒As wires on GaAs. [10][11][12][13][14][15] Since the lithographyinduced anisotropy can be externally modulated by changing the wire width 15 after the crystal growth, it enables the switching of the magnetization of ͑Ga,Mn͒As by an electric field with adjusted uniaxial anisotropy in combination with lithography-induced uniaxial anisotropies.In this Letter, we prove the presence of the lithographyinduced uniaxial anisotropy in 1-m-wide ultrathin ͑Ga,Mn͒As wires and also propose that this effect can assist in the electrical manipulation of magnetization.Devices were fabricated from a single wafer consisting of 5-nm-thin ͑Ga 0.94 ,Mn 0.06 ͒As grown on a semi-insulating GaAs substrate. Since the lattice constant of ͑Ga,Mn͒As is larger than that of GaAs, a compressive strain is built into ͑Ga,Mn͒As, which induces an in-plane magnetic easy axis.…”

“…4 Lithography-induced uniaxial anisotropy due to the magnetostriction effect has been observed in relatively thick ͑Ga,Mn͒As wires on GaAs. [10][11][12][13][14][15] Since the lithographyinduced anisotropy can be externally modulated by changing the wire width 15 after the crystal growth, it enables the switching of the magnetization of ͑Ga,Mn͒As by an electric field with adjusted uniaxial anisotropy in combination with lithography-induced uniaxial anisotropies.…”

Magnetoresistance effects and spin-valve like behavior of an arrangement of two MnAs nanoclusters

“…Additionally, planar structures can easily be integrated in magnetic non-volatile or domain wall memory devices, which also show a planar device structure. 9,10 Various spin-valve structures with different geometries based on, e.g., metals, 11,12 ferromagnetic (Ga,Mn)As alloys, [13][14][15] or Si nanowires 16 have been reported. Here, we present a different approach for planar magnetoelectronic devices using MnAs nanoclusters instead of ferromagnetic layers.…”