Here are some recent scientific and technical publications authored by our scientists and engineers. Click on the title to see the full document. These publications either describe research and development of various technologies used in our products, or were possible because of using our products in the research of the publications.

Magnetic current imaging with magnetic tunnel junction sensors: case study and analysis:

We describe the use and fabrication of magnetic tunnel junction (MTJ) sensors for the purposes of magnetic current imaging and compare the performance of MTJ sensors with other ultrasensitive magnetic sensors.

Quantitative Analysis and Depth Measurement via Magnetic Field Imaging:

Over the past several years, magnetic field imaging has been gaining popularity as a technique for fault isolation in integrated circuits and semiconductor packages, and it is used as a noninvasive, inexpensive way to visualize current throughout an IC or package

Current density mapping and pinhole imaging in magnetic tunnel junctions via scanning magnetic microscopy:  

We have applied a magnetoresistive microscopy technique to the imaging of current densities and pinhole formation in magnetic tunnel junction devices, and we demonstrate how the magnetic field distribution at the surface of the device can be used to understand the flow of current within the junction itself.

Scanning magnetoresistive microscopy for die-level sub-micron current density mapping:

In this paper, we will present a new technique for fault isolation and failure analysis in integrated circuits based on a scanning magnetoresistive imaging system. By detecting the stray magnetic fields at the surface of a chip using magnetic sensors, we are able to obtain a full map of in-plane current densities, resolving features smaller than 100 nanometers.

We have developed a scanning magnetic microscopy technique for noninvasively imaging submicron magnetic fields from embedded microscopic electrical circuits. We are able to extract from the field data a complete profile of current densities using a mathematical algorithm. As an example, we provide current density images of micron-scale passivated conductors undergoing electromigration.

Thermal stability of magnetic tunneling junctions with MgO barriers for high temperature spintronics:

Thermal stability of MgO-based magnetic tunnel junctions has been investigated from room temperature up to 500 °C, in both the memory and sensor configurations.

We have systematically investigated the dependence of tunnel magnetoresistance in MgO-based magnetic tunnel junctions as a function of Ar pressure during sputtering. We have found that the MgO surface roughness, and therefore device magnetoresistance, depends strongly on Ar gas pressure.

We have investigated the microstructures of magnetic tunneling junctions using high-resolution transmission electron microscopy (HRTEM) and have documented the effect of film roughness on the device quality.

Thermal annealing effects on low-frequency noise and transfer behavior in magnetic tunnel junction sensors:

In this article, we have investigated the low-frequency noise and transfer curve behavior in NiFe/AlOx /NiFe magnetic tunnel junction sensors as a function of the annealing temperature.

Magnetic tunneling junctions with permalloy electrodes: a study of barrier, thermal annealing, and interlayer coupling:

Magnetic properties of Ni81Fe19/Al2O3/Ni81Fe19 tunneling junctions are studied for different Al thicknesses and plasma oxidation times. Magnetometry reveals large exchange bias fields (B400 Oe) over a wide range of barrier thicknesses, indicating junctions of high quality.

Magnetic tunnel junction field sensors with hard-axis bias field:

We have fabricated and studied the magnetic properties of the Ni81Fe19 /Al2O3 /Ni81Fe19 based magnetic tunnel junction sensors and studied the effects of hard-axis bias fields on hysteresis.

In situ detection of single micron-sized magnetic beads using magnetic tunnel junction sensors:

We have demonstrated the use of highly sensitive magnetic tunnel junction (MTJ) sensors for the detection of individual micron-sized magnetic labels and explore the possible use of MTJ sensors for non-invasive immunoassay procedures.

Detection of DNA labeled with magnetic nanoparticles using MgO-based magnetic tunnel junction sensors:

We have demonstrated the detection of target DNA labeled with magnetic nanoparticles using arrays of magnetic tunnel junction sensors. These data show conclusively that MgO-based MTJ sensor arrays are very promising candidates for future applications involving the accurate detection and identification of biomolecules tagged with magnetic nanoparticles.

Bio-functionalization of monodisperse magnetic nanoparticles and their use as biomolecular labels in a magnetic tunnel junction based sensor:

Monodisperse magnetic nanoparticles (NPs) could enable the ultra-sensitive magnetic detection of biological analytes. However, rendering these particles biocompatible has remained a challenge. We report the biofunctionalization and detection of 12-nm manganese ferrite NPs. Finally, we demonstrate a novel method of detecting either protein binding or DNA hybridization at room temperature using the NPs and a magnetic tunnel-junction-based biosensor situated in orthogonal magnetic fields.

Quantitative detection of DNA labeled with magnetic nanoparticles using arrays of MgO-based magnetic tunnel junction sensors:

We have demonstrated the detection of magnetic target DNA labeled with magnetic nanoparticles (NPs) using arrays of magnetic tunnel junction sensors.

We used newly developed scanning magnetoresistance microscopy (SMRM), which measures the absolute local magnetic field from any microstructure, to observe time-lapsed magnetic domain images during magnetic switching in square Permalloy dots. This work demonstrates the novel capability of the SMRM technique and the rich switching physics of magnetic square dots.

Magnetization reversal of submicrometer Co rings with uniaxial anisotropy via scanning magnetoresistance microscopy:

We have investigated the magnetization reversal mechanism of narrow submicrometer Co rings using scanning magnetoresistance microscopy.