Nearly two years ago, the discovery of superconductivity in Nobel prize winner ‘graphene’ developed a new direction for scientific research. Superconductivity in 2D materials attracted much attention to the scientific community owing to the unique features of the effect in 2D materials namely the possibility of anisotropic dependence of superconductivity along two dimensions. In the Niobium-Carbide (Nb2C) MXene, a new member of the 2D family of graphene, no superconductivity has been reported or predicted before. Some other members of the MXene family were reported to be superconductors but their transition temperature was very low. Moreover, to measure superconductivity conveniently, they also did some extra treatments to develop a thin film design of the material which makes the process expensive. By analyzing the magnetic behavior and Meissner effect of this Nb2C material, we got a clue of the existence of superconductivity in this material. The motivation of this research was to study magnetic and superconducting behavior in newly discovered 2D Nb2C MXene which was not known to date in any form and is the first-ever report in the Meissner effect and superconductivity in as-prepared powdered Nb2C MXene. Hence, the method of material preparation is cost-effective which does not need any technologically expensive machines.
The synthesis of new 2D materials has been a challenge since the discovery of graphene which was awarded the Nobel prize owing to its cost-effective and simple way of producing it in the lab. We started working on the synthesis of new Nb2C 2D MXene using a well-optimized and cheaper synthesis tool at our research laboratory at the School of Natural Sciences (SNS), NUST. The idea behind the research was to design new 2D materials which are also superconductors in as-grown powder form which was never reported in such materials.
Superconductors – materials which, when cooled below a certain temperature (transition temperature – Tc, can carry an electric current without losing energy that provides a potential solution to the energy crisis. This also makes the material energy-efficient in terms of its magnetic properties, making it a super diamagnet that can then be employed in many applications such as magnetic train levitation. If these materials could be harnessed in spin-based devices, this can help build devices that can be employed as an energy-efficient source for free charges required to create spin-currents. The natural spin of electrons can be manipulated and detected within the current flowing from a superconductor. The results could pave the way for the use of superconductors in spintronics, I would say, super spintronics, making the devices more energy-efficient.
The research project, led by Dr. Syed Rizwan and his team member Mr. Zaheer Ud Din Babar, carried out at SNS, NUST and published in 2D Materials (Impact factor 7.343, IOP Publishing Ltd.) shows the synthesis of a new 2D superconducting material namely the Nb2C-MXene, with a record-breaking transition temperature of 12.5K which is the highest temperature all 2D MXene materials. It is a type-II Superconductor (most preferred for practical applications) exhibiting the perfect magnetic Meissner Effect (a key phenomenon for the existence of superconductivity). Significantly, we have optimized the synthesis of these 2D materials based on the simple and cheaper route that is convenient to perform in a general research lab. This reduces the synthesis cost of the material. The Meissner effect in two-dimensional material in powder form was observed which further reduces the material design cost. The fitting of critical magnetic coercive fields (Hc1 and Hc2) as a function of temperature according to the Ginzburg Landau (GL) theory and Critical current density fittings confirm the characteristic behavior of type-II superconductor. This determines further that the observed superconductor may belong to the high-Tc superconductor family and thus, resolves the quest of finding new 2D superconductors with the possibility of high TC.
Superconductivity in two-dimensional materials is fascinating in finding new Physics and is the foreground for many promising technological applications. Variety of astonishing physical phenomenon emerged in 2D materials, such as magnetism and superconductivity can revolutionize the field of spintronics and superconducting devices. It is hoped that this work would stimulate future studies to confirm the existence of superconductivity by measuring transport properties after fabricating fine 2D Nb2C MXene using novel deposition techniques. We believe this work is a significant development to explore the physical properties exhibited by 2D materials particularly the MXenes which offer unique potential for future applications in a cost-effective way.
As our Nb2C MXene was prepared in powder form, it was impossible to make adhesion of the powdered sample with the sample holder and hence, the resistivity vs. temperature (R-T) measurement could not be done and the magnetic measurement proved it to be a superconductor. We propose measuring transport properties after fabricating fine 2D Nb2C MXene films using novel deposition techniques that can help explore further properties of our material.
- The author works as an Associate Professor at the Department of Physics, School of Natural Sciences (SNS), NUST, and can be reached at syedrizwan@sns.nust.edu.pk
- The second author, Zaheer-ud-din Babar, is a student at the Department of Physics, School of Natural Sciences (SNS), NUST, and has worked under the supervision of Dr. Syed Rizwan.
