Magnetization alignment in a thin-film device

#The present disclosure relates generally to spintronics and, more specifically but not exclusively, to methods and apparatus for controllably manipulating magnetization distribution(s) in thin-film devices.

#This section introduces aspects that may help facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

#Some applications of thin-film magnetic devices rely on the ability to controllably generate the parallel and antiparallel magnetization alignment of two adjacent magnetic electrodes. More specifically, the parallel alignment corresponds to a situation in which the magnetization vectors of two adjacent magnetic electrodes are parallel to one another, i.e., pointing in the same direction or having the relative orientation angle of zero degrees. In contrast, the antiparallel alignment corresponds to a situation in which the magnetization vectors of two adjacent magnetic electrodes are antiparallel, i.e., pointing in the opposite directions or having the relative orientation angle of 180 degrees. While the parallel alignment can be generated in a relatively straightforward manner, the antiparallel alignment is significantly more difficult to generate, e.g., when the two magnetic electrodes have a nanometer-scale separation and/or are laterally adjacent to one another, rather than being stacked vertically.

#Other aspects, features, and benefits of various disclosed embodiments will become more fully apparent, by way of example, from the following detailed description and the accompanying drawings, in which:

#FIGS. 1A-1B illustrate top and cross-sectional side views of a magnetic device according to an embodiment;

#FIGS. 2A-2E show enlarged schematic top views of a constriction between two magnetic electrodes in the magnetic device of FIG. 1 according to example embodiments;

#FIGS. 1A-1B illustrate top and cross-sectional side views, respectively, of a magnetic device 100 according to an embodiment. The dashed line in FIG. 1A indicates the position of the cross-section plane BB corresponding to FIG. 1B. An example fabrication process that can be used to make magnetic device 100 is described in more detail below in reference to FIG. 12. An example method of generating parallel and antiparallel alignment of magnetization vectors in magnetic device 100 is described in more detail below in reference to FIGS. 9-11.

#Device 100 comprises a substrate 102 that supports a pair of thin-film magnetic electrodes 1101 and 1102. In some embodiments, device 100 further comprises a pair of (optional) non-magnetic, electrically conducting electrodes 1201 and 1202 that are configured to provide electrical leads to magnetic electrodes 1101 and 1102, respectively. Depending on the polarity of the voltage/current applied to electrically conducting electrodes 1201 and 1202, one of magnetic electrodes 1101-1102 may be referred to as a “source” electrode, and the other electrode may be referred to as a “drain” electrode. Magnetic electrodes 1101 and 1102 are referred to herein as “thin-film” electrodes because the electrodes' lateral dimensions indicated in FIG. 1A are significantly larger than the electrodes' thickness or height indicated in FIG. 1B. In an example embodiment, the lateral dimensions of magnetic electrodes 1101 and 1102 can be in the range between about 100 nm and about 500 nm, whereas the electrodes' thickness can be smaller than about 10 nm.

#The following materials can be used in some embodiments of device 100. Substrate 102 may comprise silicon and/or silicon oxide. Magnetic electrodes 1101 and 1102 may comprise a ferromagnetic or ferrimagnetic material. One example ferromagnetic material that can be used to make magnetic electrodes 1101 and 1102 is supermalloy, whose chemical composition can be described by the following chemical formula: Ni80Fe14Mo5X, where X is another metal. Another example ferromagnetic material that can be used to make magnetic electrodes 1101 and 1102 is permalloy. Some ferromagnetic materials suitable for magnetic electrodes 1101 and 1102 may have a tendency to form native oxide layers, such as layers 112 shown in FIG. 1B, over electrode portions exposed to ambient air for a sufficiently long period of time. Non-magnetic electrically conducting electrodes 1201 and 1202 may comprise gold, titanium, and/or other electrically conducting materials suitable for creating ohmic contacts. Various adhesion layers (not explicitly shown in FIGS. 1A-1B) can be used as known in the pertinent art to ensure good structural adhesion between the shown parts of device 100.