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Welcome to the Spintronics and Vacuum Nanoelectronics Laboratory

Marc Cahay is the Director of the Spintronics and Vacuum Nanolectronics Laboratory in the Department of Electrical AAAS  Fellow Picture of Marc CahayEngineering and Computer Science (EECS) at the University of Cincinnati (UC). His current research interests involve the theoretical and experimental investigations of spin polarized current using asymmetrically biasedquantum point contacts and the study of field emission form carbon nanotube fibers. The latter is conducted in collaboration with the group of Dr. Steve Fairchild in the Materials and Manufacturing Directorate at Wright Patterson Air Force Base. More recently, he has also been investigating novel ultracompact plasmonic nanodevices for waveguiding and nanolasing with the group of Hans-Peter Wagner in the Physics Department at UC; the fabrication of lightweight electromagnetic devices using carbon nanotube based materials with the groups of Mark Schulz and Max Rabiee at UC; and the fabrication and characterization of bolometers based on copper/graphene composites with the group of Peter Kosel in the EECS Dept. at UC.


Our laboratory has 33 year experience in the field of nanoscience and nanotechnology and vacuum micro- and nano-electronics. We have published over 145 refereed journal papers and 60 refereed conference proceedings papers in these areas. Our research has been supported by the National Science Foundation, the Air Force Office of Scientific Research, and various companies. Our director, Professor Cahay is an active member of the Electrochemical Society (ECS) for which he has co-edited of 11 proceedings volumes of symposia on quantum confinement and cold cathodes. He is also an active member of IEEE and has been on the board of the IEEE Technical Committee on Spintronics and Nano-magnetism since 2002. Over the years, he has served on the program committees of 30 international conferences.

His current research focus areas are as follows:

Multiscale Model of Field Emission from Carbon Nanotubes

We have developed a multi-scale model of field emission (FE) from carbon nanotube fibers (CNFs) which takes into account Joule heating within theFig5Cahayetal.png fiber and radiative cooling and the exchange mechanisms at the tip of the individual carbon nanotubes (CNTs) in the array located at the fiber tip. The model predicts the fraction of CNTs being destroyed as a function of the applied external electric field and reproduces many experimental features observed in some recently investigated CNFs such as, order of magnitude of the emission current (mA range), low turn on electric field (fraction of V/µm), deviation from pure Fowler-Nordheim behavior at large applied electric field, hysteresis of the FE characteristics, and a spatial variation of the temperature along the CNF axis with a maximum close to its tip of a few hundred oC. The Scanning Electron Microscope (SEM) pictures on the left show partial destruction of some of the CNTs close to the tip of the fiber as recorded after FE experiments. These pictures indicate that FE not only occur at the tip but also from the sides of the CNF.

Spintronics Using Quantum Point Contacts

Lateral spin orbit coupling (LSOC) resulting from the lateral in-plane electric field of the confining potential of a side-gated quantum point contact (QPC) (Fig.1(a)) can be used to create strongly spin-polarized current by purely electrical means1 in QPCSEM.jpgthe absence of any applied magnetic field. Using a non- equilibrium Green’s function (NEGF) analysis of a small model QPC2-5, three ingredients have been found to sufficient conditions to generate the strong spin polarization: an asymmetric lateral confinement, a LSOC induced by the lateral confining potential of the QPC, and a strong electron-electron (e-e) interaction. In the past, we have studied the evolution of anomalous conductance plateaus as a function of the potential difference between the two side gates of an In0.52Al0.48As/InAs quantum point contact in the presence of LSOC. As shown in Fig.1(b), the conductance anomalous plateau is only observed over a limited range of bias asymmetry. When the bias difference is large enough, there is a substantial increase in the electron density on one side of the narrow portion of the quantum point contact. As a result, there is an enhancement in the screening of the electron-electron interaction and the anomalous plateau disappears.


One of the figures published in the paper by T. C. Back, S. B. Fairchild, J. Boeckl, M. Cahay, F. Derkink, G. Chen, A. K. Schmid, A. Sayir, “Work Function Characterization of the Directionally Solidified LaB6–VB2 Eutectic”, Ultramicroscopy 183, 67 (2017), was used as a front cover of the December 2017 issue of the journal Ultramicroscopy.

  • Cahay and Kevin Jensen (Naval Research Laboratory, Washington DC) will be the co-chairs of the joined International Vacuum Nanoelectronics Conference/International Vacuum Electron Sources Conferences to be held in Cincinnati in July 2019.
  • Cahay received a DAGSI (Dayton Area Graduate Studies Institute) grant for the project entitled “Hybrid Materials For Advanced Pulsed Laser Power Devices”. The project will sponsor part of the PhD work by Jonathan Ludwick who joined the lab of Prof. Cahay in the Fall of 2017.
  • Cahay received the 2017-2018 Faculty Career Award at UC.