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Multiferroic Material for Next-Generation Memory Device
The field-driven switching of the ferroelectric and ferromagnetic properties forms the basis of ferroelectric random-access memory (FERAM) and magnetic random-access memory (MRAM) devices respectively. Both devices are non-volatile and have certain advantages over conventional random-access memory devices (RAMs).
The term "multiferroic" refers to materials that simultaneously possess ferromagnetic and ferroelectric properties. In a multiferroic material with strong magnetoelectric coupling, the polarisation or magnetisation will be switchable with respect to magnetic field or electric field. Therefore, the shortcomings in FERAM and MRAM could be avoided by employing suitable multiferroic materials, such that low energy ferroelectric writing and non-destructive magnetic reading could be achieved.
Currently, there has been no single-phase bulk material reported that demonstrates long-range ordered switchable polarisation and magnetisation at room temperature. This technology presents a new and improved single-phase material that exhibits magnetoelectric effect over the typical operational temperature ranges (e.g. at room temperature) of electronic devices.
Technology Features, Specifications and Advantages
This technology presents a new multiferroic material that exhibits both ferromagnetic and ferroelectric properties at room temperature. The material comprises of a transition metal oxide, taking the form of thin films deposited on a substrate suitable for most electronic applications.
The multiferroic compound, Molybdenum Oxy-telluride (MoOxTey), can be grown based on vapor-trapped two-step chemical vapor deposition (VTCVD). In the VTCVD process, gases are used to carry molybdenum precursors mixed with sodium cholate and tellurium powder to grow high-quality, 2D large-scale MoOxTey crystals on SiO2/Si substrate. The principle of controlling the relative compositions is applicable to other growth methods, such as Molecular Beam Epitaxy (MBE), Metal Organic Chemical Vapor Deposition (MOCVD) or laser ablation deposition.
Both ultrathin films as well as thick films of the material can be grown by adjusting the growth conditions. The film has been shown to have an adjustable thickness of up to a hundred nanometres and are stable under ambient conditions. It also exhibits low sheet resistance and quick, switchable polarisation at room temperature—showing promise for incorporation into various electronic devices.
This technology is applicable to semiconductor and memory manufacturers. For example, the multiferroic thin film can replace the magnetic electrode of the MRAM or the ferroelectric film of the FERAM, while the other device structures remain unchanged.
Besides Molybdenum (Mo), other transition metals such as Tungsten (W), Niobium (Nb) or Vanadium (V) can be used. The transition metal oxide material can also be doped with other elements from group 16 such as Selenium (Se), Polonium (Po) and Livermorium (Lv), besides Tellurium (Te).
- Allow switchable polarisation and magnetisation at room temperature, resolving the shortcomings and combining the strengths of FERAM and MRAM technologies
- Can be formed into thin films using existing deposition techniques with thickness of up to a hundred nanometers
- Low sheet resistance and a short switching time, making the material suitable for data storage, memory and other applications