27-Oct-2022: India’s first indigenous Overhauser Magnetometer may show the way towards reducing costs of sensing experiments essential for geomagnetic sampling
Indian scientists have developed an Overhauser Magnetometer, one of the most accurate magnetometers extensively used by all magnetic observatories around the world, making way for reducing the cost of sampling and sensing experiments essential for geomagnetic sampling. The sensor installed at Alibag Magnetic Observatory (MO) can absolve India’s dependence on commercial OVH magnetometers for performing geomagnetic field measurements.
OVH magnetometers are known for their higher accuracy, higher sensitivity, and efficient power consumption and hence find applications in all magnetic observatories worldwide as well as in international space programs. It has so far been imported for such purposes in India.
In order to reduce dependence on imports, the Indian Institute of Geomagnetism (IIG), an autonomous research institution under DST, Government of India, has developed the magnetometer as part of its technology development program.
A team from IIG’s instrumentation division used various spectroscopic tools and theoretical simulations to understand the working of the OVH sensor. They further performed various control experiments, such as varying the sensor composition and examined the sensor’s performance. This helped them to optimize the sensor parameters and its associated electronics, which finally led to a very efficient and stable OVH sensor.
Experiments with the sensor installed at the Alibag Magnetic Observatory (MO) for geomagnetic sampling found that the sensor reproduced the geomagnetic diurnal variations accurately and precisely showed the signatures of various space weather events such as geomagnetic storms, sudden impulses, etc. The performance of this indigenously made magnetometer is at par with a commercial OVH sensor that is currently installed at the magnetic observatories of IIG.
The sensor is currently being tested for its long-term stability. The group is further excited to adapt their sensor for the outer space environment to support the existing Indian space research program. In addition, the group feels that the understanding of this project, specifically the underlying mechanism of Dynamic Nuclear Polarization (DNP), would also be of potential help to develop a sensitive magnetic resonance imaging (MRI) instrument.
5-Jul-2022: New material discovered can convert infrared light to renewable energy
Scientists have discovered a novel material that can emit, detect, and modulate infrared light with high efficiency making it useful for solar and thermal energy harvesting and for optical communication devices.
Electromagnetic waves are a renewable energy source used for electricity generation, telecommunication, defence and security technologies, sensors, and healthcare services. Scientists use high-tech methods to manipulate such waves precisely -- in dimensions that are thousands of times smaller than the human hair, using specialized materials. However, not all the wavelengths of light (electromagnetic waves) are easy to utilize, especially infrared light, since it is difficult to detect and modulate.
For infrared light applications, intelligent and cutting-edge materials are required which can enable excitation, modulation, and detection at desired spectral range with high efficiencies. Only a few existing materials can serve as hosts for light-matter interactions in the infrared spectral range, albeit with very low efficiencies. The operational spectral range of such materials also does not cover industrially important short wavelength infrared (SWIR) spectral range.
In a significant development, researchers from Bengaluru’s Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), an autonomous institute of Department of Science and Technology (DST) have discovered a novel material called single-crystalline scandium nitride (ScN) that can emit, detect, and modulate infrared light with high efficiencies.
K. C. Maurya and co-workers have utilized a scientific phenomenon called polariton excitations that occur in tailored materials when light couples with either the collective free electron oscillations or polar lattice vibrations to achieve this feat. They have carefully controlled material properties to excite polaritons (a quasi-particle) and achieve strong light-matter interactions in single-crystalline scandium nitride (ScN) using infrared light.
These exotic polaritons in the ScN can be utilized for solar and thermal energy harvesting. Also, belonging to the same family of materials as gallium nitride (GaN), scandium nitride is compatible with modern complementary-metal-oxide-semiconductor (CMOS) or Si-chip technology and, therefore, could be easily integrated for on-chip optical communication devices.
“From electronics-to-healthcare, defense and security-to-energy technologies, there is a great demand for infrared sources, emitters and sensors. Our work on infrared polaritons in scandium nitride will enable its applications in many such devices,” said Dr. Bivas Saha, Assistant Professor at JNCASR. Apart from JNCASR, researchers from the Centre for Nano Science and Engineering from the Indian Institute of Science (IISc.) and the University of Sydney also participated in this study published recently in the scientific journal Nano Letters.
8-Jun-2022: Neutral electron flow detected in Graphene could shape future quantum computation
Physicists studying have detected counter propagating channels in two layered graphene along which certain neutral quasiparticles move in opposite directions breaking conventional norms. The detection has potential to shape the future quantum computation.
When a strong magnetic field is applied to a 2D material or gas, the electrons at the interface – unlike the ones within the bulk – are free to move along the edges in what are called edge modes or channels – somewhat similar to highway lanes. This phenomenon called the quantum Hall effect has given rise to a platform for hosting exotic emerging quasiparticles, with properties that could lead to exciting applications in area of quantum computing. This edge movement, which is the essence of the quantum Hall effect, can lead to many interesting properties depending on the material and conditions.
For conventional electrons, the current flows only in one direction dictated by the magnetic field (‘downstream’). However, physicists had earlier predicted that some materials can have counter-propagating channels where some quasiparticles can also travel in the opposite (‘upstream’) direction. However, these channels they have been extremely difficult to identify because they do not carry any electrical current.
In a new study, researchers from the Indian Institute of Science (IISc) have provided “smoking gun” evidence for the presence of upstream modes along which certain neutral quasiparticles move in two-layered graphene. To detect these modes or channels, the team used a novel method employing electrical noise – fluctuations in the output signal caused by heat dissipation. The research supported by Science and Engineering Research Board (SERB), a statutory body under the Department of Science and Technology (DST), has been published in the journal Nature Communications.
“Though the upstream excitations are charge-neutral, they can carry heat energy and produce a noise spot along the upstream direction,” explains Dr. Anindya Das, Associate Professor in the Department of Physics, Indian Institute of Science, and corresponding author of the study published in Nature Communications.
In the current study, when the researchers applied an electrical potential to the edge of two-layered graphene, they found that heat was transported only in the upstream channels and dissipated at certain “hotspots” in that direction. At these spots, the heat generated electrical noise could be picked up by an electrical resonance circuit and spectrum analyzer.
“The detection of “upstream” modes, is critical for the emergent modes with exotic quantum statistics, which has potential to shape the future flaunt-tolerant quantum computation.”