Manipulating relaxation rates in magnetic materials at gigahertz frequencies

Lead Inventors: William E. Bailey, Ph.D.Problem or Unmet Need:Magnetic devices such as sensors, magnetic tunneling junctions and spin valves are headed toward nanoscale miniaturization. They are also frequently used at gigahertz (GHz) operating frequencies. Under these conditions it is predicted that the critical signal-to-noise ratio is inversely proportional to the damping constant at the GHz frequencies. Although prior work has shown that damping constants can be changed by introduction of rare-earth impurity atoms, such manipulations have only resulted in an increase in the damping constants. This technology provides the materials and methods to reduce damping constants in thin films in a wide range of devices and components. This invention details the method by which a thin film of magnetic material (e.g., iron) is alloyed with titanium (Ti), vanadium (V), chromium (Cr), and manganese (Mn) (i.e., lower Z transition metal elements than iron) is to reduce the relaxation rate of the ferromagnetic thin film. Alternatively, any other suitable element from group V or VI can be chosen. When vanadium is chosen, an alloy with the composition of Fe1-xVx, preferably with 'x' between 0 and 0.33, is formed. Such a thin film has been observed to reduce the damping constant significantly. The choice of the alloying element is arrived at by observing if there is a reduction in the gyromagnetic ratio (g) in iron with the introduction of the element through estimations from Einstein-de-Haas measurements. It should be noted that the method can be applied to metals other than iron (e.g., nickel, cobalt) as well as alloys (e.g., Permalloy).

Increased frequency ranges for devices using thin films Easy process integration (room temperature deposition) of these thin films can replace monolithic ferrite elements glued to chips in communications industry Device integration will lead to reduced fabrication cost and increased reliability

Magnetic memory (MRAM) Spin electronics ('spintronics') Giant magnetoresistive and tunnel magnetoresistive sensors On-chip gigahertz elements (e.g., circulators and filters) in telecommunication and cellular devices Magnetic read heads Improved radio frequency identification (RFID) tags

This invention details the method by which a thin film of magnetic material (e.g., iron) is alloyed with titanium (Ti), vanadium (V), chromium (Cr), and manganese (Mn) (i.e., lower Z transition metal elements than iron) is to reduce the relaxat...

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