Dr. Vadym Zayets

• Developing of optical non-volatile memory with operation speed above 1 TBit/sec, where the data recorded by photo-excited spin-polarized electrons.

• Developing of non-reciprocal magneto-optical devices, such as an optical isolator and optical circulator, which can be integrated into optoelectronic integrated circuits.(plasmonic isolator, hybrid isolator, CdMnTe isolator).

• Developing of a transistor, in which a semiconductor is replaced by a metal, for a dense 3D integration of electronic circuits.

• Study of the Voltage-control magnetism (VCMA effect)

• Integration of optical devices, which is made of a Si nanowire waveguide and plasmonic waveguide, into a dense Photonic Integrated Circuit (PIC)

• Study of the Spin Hall effect, the Spin-Hall resistance and the spin-orbit torque (SOT)
  

• "Excellent Research Price" of Magnetic Society of Japan, 2004.09

• Award of Ukraine cabinet council for young researchers, 1995
  

• "Next generation magneto-optical element for broadband networks", Industrial, technological research promotion with cooperation with Photo-Crystal Co. Ltd, NEDO， 2001-2006, 100,000,000 yen, 5 years (Initially 3 years, extended to 5 years due to successful results).(Final report)

• "Spin-light function element for high-speed networks", The Ministry of Education, Culture, Sports, Science and Technology (MEXT) young researchers promotion project，2001-2006, 70,000,000 yen 5 years. (Final report 1) , (Final report 2)

• "Spin-photon nonvolatile memory". Industrial, technological research promotion，NEDO，2006-2009, 60,000,000 yen, 3 years.

• "Plasmonic isolator for Photonic Integrated Circuits (PIC)" Kahenhi, 2016-2019 20,000,000 yen, 3 years

• 1) Realization of a semiconductor-based magneto-optical waveguide isolator for high-speed optical network .
  Magnetic garnets are used as a magneto-optical material for isolator, but the integration of the isolator with semiconductor laser diode and amplifier was impossible, because incompatibility of the magnetic garnets with semiconductors. I proposed to use diluted magnetic semiconductor (DMS) as a material for the waveguide optical isolator. Due to the high quality of the film and optimized device structure, I obtained the low optical loss, high Faraday effect, low dispersion of magneto-optical constants, high magneto-optical figure-of-merit and high isolation in wide wavelength range. Performance of DMS isolator, which was fabricated on semiconductor substrate, was better that that of conventional garnet isolator.

• 2) Proposal of ferromagnetic-metal-semiconductor amplifier hybrids as new spintronics optical function devices
  Ferromagnetic metals have large magneto-optical effect. However they have never been used for magneto-optical device for optical communication because of their huge optical loss. I have proposed a new idea, i.e. ferromagnetic-metal-semiconductor amplifier hybrids . It can work as an optical isolator that can be very small and integratable into optoelectronics circuits with a simple process. My proposal attracted much attention, and some groups of Tokyo University and IMEC, Belgium (European Isolaser project) have started up research projects to realize it. In 2004, I demonstrated isolation effect in the hybrid isolator.

• 3) Realization of Room-Temperature magnetic semiconductors.
  While ferromagnetic semiconductor is indispensable for spintronics applications, its ferromagnetic Curie temperature has been far below room temperature. Several years ago, my group succeeded to create a first room-temperature ferromagnetic semiconductor (Zn,Cr)Te. I did an essential contribution to this work by using my ability to grow high quality magnetic semiconductors films.

• 4) Proposal on non-volatile optical memory with operational speed above 1 TBit/sec. Magnetic random access memory (MRAM) is quickly emerging technology. However, any magnetic memory has limitation of recording speed due to the magnetization reversal time (500 -2000 ps). To overcome this problem, in 2004 I invented new type of non-volatile optical memory, which is expected to operate at speed of several TBit/sec. It uses unique properties of light-spin interaction. Demultiplexing at 2.2 TBit/sec was already demonstrated. Functions of reading, writing and multiplexing function were demonstrated, studied and optimized.

• 5) Fabrication of a plasmonic isolator for Photonic Integrated Circuits (PIC)

• 6) Proposal on transistor, in which a semiconductor is replaced by a metal, for a dense 3D integration of electronic circuits.

• 7) High-precision measurements of the voltage controlled magnetism in ferromagnetic nanowires.

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Major Skills :

1) Nano- and micro fabrication (see here)

• design and optimization a multi-layer fabrication process, which involves several steps of a photo-lithography (a stepper) and a EB lithography and a high precision alignment;
• I am an expert in EB lithography. (a) fabrication of a ultra-small device (size~ 30-50 nm); (b) fabrication of a complex device of a complex shape; (c) fabrication of long devices (nanowire waveguides); (d) a precise alignment (~10-20 nm) between different steps of EB lithography
• growth a high- quality thin films of III-V semiconductors ((AlGaIn)(AsP)), II-VI semiconductor (CdZnMnCrTe), ferromagnetic metals (FeCoB,FeBTb) and oxide (MgO) using MBE and sputtering methods.

2) Optical measurements

• fiber/waveguide measurements. (a) high-precision alignment (b) high-speed evaluation ( up to 100 GHz); (c) fabrication of a semiconductor waveguide, a semiconductor optical amplifier, a semiconductor laser diode, a Si nanowire waveguide and a plasmonic waveguide
• pump-probe measurements (a) conventional pump-probe (b) phase-locked pump-probe (c) fiber-based pump-probe.

3) Automatization of experiment and fabrication technology

• Software. I am expert in LabView, VisualBasic and Visual C++.
• Multi- instrument automatic measurements. High-speed automatic measurements
• Automatization of the fabrication technology

4) Magneto-transport measurements

• Evaluation of nano-size spintronics devices
• High-precision measurements of coercive field (~0.1 Oe), anisotropic field, retention time, effective magnetization and delta using the Hall effect