RESEARCH
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Multiferroic and Magnetoelectric Materials for the data storage device
Quantum Materials towards application of Qubit- Single-ion-magnet
Strongly Correlated systems--- Investigation through Neutron diffraction, Inelastic Neutron Scattering, and SR spectroscopy.
Multiferroic Quantum Criticality
Magnetocaloric Materials-- use in the magnetic refrigerator
High-k and low-loss dielectric material ( for alternative energy )
Ionic Control of Materials (Electrolyte Gating using Ionic Liquid/Gel)
Investigation of strongly correlated electron systems through X-ray, muon-SR, and Neutron spectroscopy.
Metal-organic-framework – a new approach towards multiferroicity
Thermoelectric materials- for reuse of thermal energy in thermal power plant
Unconventional s-orbital state of Tb and cooperative Ru(4d )-Tb(4f ) spin-ordering
Ekta et al., (Journal of Materials Chemistry C, 2025)
We resolve the intriguing spin-structure of a 4d-4f system, Ba3TbRu2O9, which shows a cooperative spin-ordering of both Ru(4d) and Tb(4f), not commonly observed in d-f coupled systems. We demonstrate an unconventional s-orbital state of terbium (4f-ion), exhibiting zero orbital moment (L=0), and an S=1 ground state of ruthenium with full spin moment, in contrast to all other members in this family.
Demonstration of Spin-driven ferroelectricity through Neutron Diffraction
Correlated Quantum Material Ba3HoRu2O9--- Mechanism of spin-driven ferroelectric- A schematic diagram (arXiv: 2309.13465 ) Phys. Rev. B 109,224418(2024)
Magnetic and electric materials have contributed considerably to the development of modern technology, with components for data-storage devices being the most outstanding examples. Now, it is realized that a single material, which exhibits both magnetic and electric ordering (a so-called ‘multiferroic’ material), could perform multiple tasks and holds promising potential for future technological applications. Specifically, multiferroic materials with strong magnetoelectric (ME) coupling, in which magnetism (or electric polarization) can be controlled via an electric (or a magnetic) field, are promising materials due to its possible potential application in data-storage technology. Therefore, the search for functional materials of this type is in focus of current research due to their technological importance. Most of the reported bulk single multiferroic materials are based on 3d-transition metal oxides, which exhibit low temperature multiferroic ordering and weak ME coupling. However, systems containing 4d/5d-transition metal oxides should be potential candidates due to their compelling effects of extended d-orbitals and larger spin-orbit coupling to enhance multiferroic ordering and ME coupling. Moreover, in the case of the inverse Dzyaloshinskii-Moriya (DM) interaction and spin-dependent p-d hybridization, the strength of the ME coupling depends on several factors, one of which is the spin-orbit coupling, where a larger spin-orbit coupling gives rise to larger polarization. It has been theoretically predicted that 3d-5d double perovskite systems could serve as better multiferroics, where the higher d-orbitals will potentially enhance both the ordering temperature and the ME coupling. But one of the drawbacks is that most of the 4d/5d-orbital based systems are electrically leaky (less insulating). This is counterproductive for multiferroic samples, as this hinders both dielectric and ME investigation and is further detrimental for the practical applications. Therefore, experimental realizations of bulk magnetoelectric multiferroic materials containing magnetic (non-d0) 4d/5d-orbitals are rare due to the scarcity of good insulating materials.
We design new ME materials containing 4d-4f orbitals and investigate via bulk (magnetic, dielectric, ferroelectric) and spectroscopic (X-ray and Neutron scattering) investigations, which will find a route towards enhancement of multiferroic ordering temperature and ME coupling strength in a single material to enable potential application in a long-run.
Probing the intriguing magnetic ground state of Ruthenates (4d-materials)
Ekta Kushwaha et al., (under review)
The Ruthenates exhibit an intriguing magnetic ground state due to the interplay between the large crystal electric field, pronounced spin-orbit coupling, and strong electronic correlations of 4d-orbital. A small crystallographic distortion plays a crucial role in determining the magnetic ground state and spin structure. Our group is focused on probing the fascinating ground state and exploring underlying physics through Neutron diffraction and Inelastic Neutron scattering. Further, we probe the local lattice geometry and minute distortion through combined synchrotron XRD and X-ray absorption spectroscopy.
Demonstration of Quantum phenomenon in a prototype quantum qubit material through Neutron Scattering
2D contour colour plot of INS spectra at 7.6 K,
Gourab Roy, et al. (to be submitted)
Spin Relaxation mechanism through Orbach Process in Single-ion magnet
The search for Single-Ion Magnetism (SIM), crucial for quantum qubits, unveils how bi-stability between ∣MJ∣ = ±5/2 is sustained at zero field in our recent research. This stability is physically demonstrated through the dominant Orbach spin-relaxation mechanism via strong spin-phonon coupling, arising from the high spin state (S = 3/2, L = 1) of Co(II) and high uniaxial anisotropy.
Magnetocaloric effect (MCE) in strongly correlated d-f materials
Mohit Kumar et al., (under review)
Mohit Kumar et al., (under review)
The quest for developing magnetocaloric materials with enhanced efficiency at low magnetic fields and discovering new materials that exhibit the magnetocaloric effect near room temperature is crucial for advancing energy-efficient cooling technologies and sustainable thermal management solutions.
Our motivation is to design magnetocaloric materials that can operate over a broad temperature range, enabling versatile and efficient cooling applications.
We design oxide magnetocaloric materials and investigate them through bulk and microscopic techniques using synchrotron X-ray and Neutron as a probe.
Investigating the complex magnetism and spin dynamics of Correlated Quantum Materials using muon spin relaxation spectroscopy as a local magnetic probe
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