Dr. Rizwan Nabi : Developing Single-Molecule Magnets For High Density Data Storage

This is the tenth part of the series called ‘Scientist Says’ where we bring for our readers the significant research works of young scientists in various fields.

Dr. Rizwan Nabi completed his Ph.D in June 2020 at IIT Bombay (India) under the supervision of Prof. Gopalan Rajaraman. Presently, he is working as a Research Associate “European Research Council Fellow” in the Department of Chemistry at The University of Manchester. He talks about his research with Rashida Bakait of India Tomorrow.

 Q. Please briefly explain your research.

Ans. My research broadly focuses on the Single-Molecule Magnets. Single-Molecule Magnets (SMMs) are the metal-organic compounds (complexes) which show magnetic relaxation of purely molecular origin below a certain blocking temperature. In this temperature range, a SMM exhibits magnetic hysteresis of purely molecular origin. In contrast to conventional bulk magnets and molecule-based magnets, collective long-range magnetic ordering of magnetic moments is not necessary.  Organometallic molecules have emerged as clear front-runners in the search for high-temperature single-molecule magnets. Within this family of structurally similar molecules, significant variations in their magnetic properties are seen, demonstrating the importance of understanding magneto-structural relationships to develop more efficient design strategies. Efforts in this field primarily focus on raising the operating temperatures of single-molecule magnets to liquid nitrogen temperature or room temperature in order to enable applications in magnetic memory. Apart from the higher blocking temperature, efforts are being made to develop SMMs with high energy barriers to prevent fast spin relaxation. Recent acceleration in this field of research has resulted in significant enhancements of single-molecule magnet operating temperatures to above 70 K.

Q. What was the objective of your research?

Ans. The Main objective of my research is to check the stability and hence magnetic properties of the SMMs on different surfaces like Au(111) and many other surfaces like MgOAg(100), carbon based surfaces (graphene and graphite). Here we are trying to develop an ab initio spin dynamics methodology and check if it is capable of quantitative prediction of relative relaxation rates in the Raman/Orbach regions. The ultimate goal of our study is to develop a SMMs which can be fully modified to develop a high density data storage memory devices, qubits or spintronic devices. The ultimate miniaturization of classical memory devices lies in the use of atoms or molecules to store binary data. Single molecule magnets (SMMs), molecules that exhibit slow magnetic relaxation and memory effects, provide a flexible platform for realizing high-density data storage.

Q. When did you begin and complete your research?

Ans. I started my research after joining Indian Institute of Technology, Bombay in July 2014 as a Ph.D student in the department of Chemistry. I completed my Ph.D in June 2020.I have completed my Ph.D  at IIT Bombay (India) under the supervision of Prof. Gopalan Rajaraman. My research lay emphasis on describing magnetic properties in 3d and 4f SMMs on different surfaces such as Au (111), MgO/Ag(100), and studying cobalt complexes for spin filtering purposes. Currently, my research interests revolves around computational study of the chemical control of the vibronic coupling of SMMs. Fortunately, recent theoretical efforts have begun to establish robust and systematic methodologies to treat these problems, targeting a new approach of engineering spin−phonon coupling.

Q. What  were the findings of your research?

Ans. Our  group looks into the stability of SMMs on surfaces which is a great challenge itself if one wants to develop memory devices from the SMMs. Our findings are published in peer reviewed journals like American Chemical Science (ACS) and Royal Society of Chemistry (RSC), where we have discussed how challenging it is to study these SMMs on various surface. We have reported Lanthanide complexes as molecular dopants for realizing air-stable n-type graphene logic inverters with symmetric transconductance which is published in the Journal of Material Horizon . Also, we are the first to report a large molecule with 19 Metal ions on gold surface using DFT calculation as Deciphering the origin of variation in the spin ground state and oxidation state of a {Mn19} cluster on Au (111) surface: is the Au (111) surface innocent. This study is published in the Journal of Chemical Communication which is a Royal Society of Chemistry Journal.

Q. What was the conclusion of your research?

Ans. In order to develop memory devices from SMMs one needs to check the stability of these SMMs on various surface for the purpose of device fabrication. There are tremendous SMMs which are stable as pristine molecules but loose SMM features upon grafting which can be due to various reasons like charging effect of surfaces, change in the geometry of the molecules on surface, spin-phonon interactions etc. Thus, while fabricating one needs to be sure enough about these challenges and how to stabilize these molecules on surface.

Q. Any scholarships or awards for research?

Ans. I have been awarded European Research Council award as a Post-Doctoral Fellow at The University of Manchester (UK).

Q.  What  challenges did you face?

Ans. Challenges are an integral part of the research. There are many things associated with the research apart from the things which one learns from the books or some other sources. One needs to be fully motivated to work as a researcher. You may feel down at times but you need to have guts to work and find the loopholes. It’s never a well beaten path to walk on, one needs to set his/her target and work day and night to get that achieved. You need to balance your social life and life as a researcher which is quite challenging itself were many people fail. I have faced problems in designing a DFT protocol for stabilizing these molecules on particular surfaces, which is not an easy task to do with DFT. You never know which surface will suit your molecule unless you do some calculations, thus your study may be time consuming since lot of problems need to be addressed.

 Q. How do you think your research would be beneficial to the industry or society?

Ans. Modern magnetism or SMMs is in general quite a fascinating field, which aims at developing memory devices which can be used for the high density data storage, qubits and quantum computing. Once the stable SMMs have been obtained at room temperature (which is yet a dream to be achieved), this will revolutionise the modern data storage limits and also the future aspects of the super computers. Modern electronic gadgets (cell phones, laptops and iPad) will be improvised when the SMMs will be stabilized at the room temperature. This way our study would be beneficial not only to the industry but also to the common people.

Q. Any new research you are working on now?

Ans. Currently, the core objectives of my research programme are to develop a modern theory of solid state vibronic coupling and to determine how vibronic interactions can be controlled with chemistry. This can be achieved by undertaking an integrated computational and experimental research programme in tandem.

Q. How do you think your research can be carried forward?

Ans. Designing molecules with better SMM features using the state -of –the- art principle and targeted design criteria together with the knowledge of DFT and ab initio studies can help to reach a particular target of obtaining memory devices. Moreover, the stability at room temperature by increasing the blocking temperature and effective energy barrier to the relaxation of magnetization can help better to move this study to next levels. Also, stability on a particular surface will produce better results.

Q. Please give few suggestions for the budding scientists.

Ans.  I would suggest budding scientists to not to lose hope in any circumstances. Work hard and maintain consistency in research. Challenges may come but we need to face them with a smile.