Magnetic Quantum-Mechanical Tunneling
Magnetic tunnel junctions (MTJs) are a new class of thin film device which was first successfully fabricated in the mid-1990s. In its simplest form, the MTJ is a tri-layer “sandwich”consisting of two layers of magnetic material separated by an ultra-thin insulating film. If a voltage is applied to the top and bottom of this structure, classical physics does not allow a current to flow; however, if the insulating layer (also referred to as the “barrier layer”) is sufficiently thin, electrons can flow by quantum mechanical tunneling through the barrier layer.
The reason for the relative newness of this technology is that, for devices with a reasonable resistance values, the thickness of the insulatingbarrier layer must be extremely low (0.7 -1.6 nanometers, or 4-10 atomic monolayers). For tunneling between two magnetized materials, the tunneling current is maximum if the magnetization directions of the two electrodes are parallel and minimum then they are aligned anti-parallel. Therefore,the tunneling current, and therefore the resistance of the device, will change as external magnetic fields alter the magnetic orientation of these twoelectrodes.
For the full article on Magnetic Tunneling Junctions, Click Here.
(Magnetic) Spintronic Immunoassay
Current research focuses on developing a magnetic biosensor, a device that can detect the presence of virtually any particle in your body, foreign or natural. By utilizing tiny magnetic nanoparticles to tag the DNA, viruses, bacteria, or cancer cells in question, it is possible to detect the exact concentration of almost any molecule or particle present in the body.
How it works is relatively simple. First, magnetic nanoparticles (NPs) that bind only to specific molecules are fabricated. These NPs are then introduced into the sample to be tested. If the molecules, viruses, DNA, or other cells which the NPs are designed for are present, the NPs will be tightly bound to or inside them.
Later, the biological sample will be introduced to an array of magnetic sensors with “probe” molecules (antigens, compliementary DNA) on each sensor. These probe molecules will bind tightly to certain compounds in a sample if they are present, and the compounds that do not bond to the probe molecules will be washed away. The sensor can then detect the presence of these NPs by sensing their magnetic field. The sensor would then produce a signal confirming their existence. The strength of the signal is proportional to the concentration of such molecules. The biomagnetic sensor is so sensitive that even a single biomolecule can be detected.
For the full article on Spintronic Immunoassays, Click Here.
Magnetic Current Imaging Technology
With spintronic analysis, it is possible to create a magnetic imaging tool which uses the tiny magnetic fields emitted by all of the currents inside any chip to understand the inner workings of the circuitry– without the need to process or eventouch the device at all. Using mathematical algorithms which convert the magnetic field data into a full distribution of current density,this system allows the user to see a map of all of the current flowing on every level of the device, down to the single microamp level. Because the current is the lifeblood of an integrated circuit, this map can be invaluableto engineers and technicians attempting to understand the nature of the problem.
Some common problems which are quickly diagnosed and/or located using our magnetic technique are:
• power-to-ground shorts
• pin shorts
• hot spots
• localized and global leakage
• excessive current draw
• dielectric integrity issues
For the full article on Magnetic Current Imaging, Click Here.