In the NIST sensor design, ruthenium modulates interactions between a ferromagnetic film (in which electron “spins” all point in the same direction) and an antiferromagnetic film (in which different layers of electrons point in opposite directions to stabilize the device).
In the presence of a magnetic field, the electron spins in the ferromagnetic film rotate, changing the sensor’s resistance and producing a voltage output. The antiferromagnetic film, which feels no force because it has no net magnetization, acts like a very stiff spring that resists the rotation and stabilizes the sensor. The ruthenium layer (see graphic) is added to weaken the spring, effectively making the device more sensitive. This makes it easier to rotate the electron spins, and still pulls them back to their original direction when the field is removed.
NIST tests showed that thicker buffers of ruthenium (up to 2 nanometers) make it easier to rotate the magnetization of the ferromagnetic film, resulting in a more sensitive device. Thinner buffers result in a device that is less sensitive but responds to a wider range of external fields. Ruthenium layers thicker than 2 nm prevent any coupling between the two active films. All buffer thicknesses from 0 to 2 nm maintain sensor magnetization (even resetting it if necessary) without a boost from an external electrical current or magnetic field. This easily prevents demagnetization and failure of a sensor.
The mass-producible test sensors, made in the NIST clean room in Boulder, Colo., consist of three basic layers of material deposited on silicon wafers: The bottom antiferromagnetic layer is 8 nm of an iridium/manganese alloy, followed by the ruthenium buffer, and topped with 25 nm of a nickel/iron alloy. The design requires no extra lithography steps for the magnetic layers and could be implemented in existing mass-production processes. By contrast, the conventional method of modulating magnetoresistive sensors—capping the ends of sensors with magnetic materials—adds fabrication steps and does not allow fine-tuning of sensitivity. The new sensor design was key to NIST’s recent development of a high-resolution forensic tape analysis system for the Federal Bureau of Investigation (see Magnetic Tape Analysis “Sees” Tampering in Detail).
Laura Ost | EurekAlert!
SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University
Molecule flash mob
19.01.2017 | Technische Universität Wien
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences