Condensed Matter Physics Division (CMPD) is comprised of three sections, namely, Light Scattering Studies Section, Low Temperature Studies Section and High Pressure Studies Section.
CMPD is dedicated to perform basic and applied research on the structural, lattice, electronic, magnetic and optical properties of hard and soft condensed matters under extreme conditions of temperature, pressure and magnetic fields; Further, over the years various facilities for the synthesis of novel, superhard materials have been established including a Laser Heated Diamond Anvil Cell (LHDAC) facility. The systems under investigation encompass nuclear materials, superconductors, strongly correlated systems, magnetocaloric materials, topological insulators, multiferroics, energetic materials, frustrated systems, f-electron based intermetallics and oxides, glasses and super hard transition metal borides.
Research is also pursued to investigate emergent phenomena and proximity effects in heterostructures. Dynamic light scattering and confocal microscopy are utilized for studies on soft condensed matter. Optical trapping and manipulation of mesoscopic particles using holographic optical tweezers (HOTs) to study inter-particle interactions in colloidal suspensions/biological systems are being pursued. Besides there is also an intense effort towards quantum metrology based research studies using entangled photons, pump-probe spectroscopy & quantum optics.
Achievements
Basic Research
Photonic hydrogels for Uranium extraction: Microgel based photonic hydrogels have been synthesized and studied for monitoring and extraction of Uranium in aqueous solutions. Using these hydrogels, uranium extraction capacity of~ 487 mM/kg with response time (300 min) have been achieved. To improve the response time further, homogeneous silica based photonic hydrogels have been synthesised. The response time has been improved by ~ 10 times (30 min.).
Investigation of phonon modes in secondary explosives: Phase transformations and sensitivity on three insensitive secondary explosives have been investigated in collaboration with DRDO, Govt. of India. Elastic and phonon-mode anomalies with temperature in the energetic material TEX (C6H6N4O8) studied by Brillouin spectroscopy provided direct experimental evidence of anomalous reduction in its elastic constant by ~5 GPa from 20-80oC.
Studies on elastic and optical properties glasses: Tuning of structure at different length-scales by varying composition in tellurite and borate glasses to achieve better elastic and optical properties was carried out. Structural changes were also studied under the influence of pressure and temperature in these glasses.
Complex beam shaping : A q-plate with passively tunable retardance has been designed and experimentally demonstrated. A scheme for designing doubly inhomogeneous wave-plates for various complex beam shaping tasks and a polarimetric method of realizing higher-order LG and HG beams from fundamental Gaussian light beams has also been devised.
Studies on bulk and thin films of BSCCO based high-temperature superconductors:? The effects of high pressure and Pb substitution on the structure and superconducting properties of two coexisting phases, namely Bi-2212 and Bi-2223 in the BSCCO superconductor have been studied. Studies on thin films of Pb doped Bi1.75Pb0.25Sr2Ca2Cu3O10+δ (B(Pb)SCCO) superconductors grown on different substrates revealed an enhancement of Bi-2223 phase fraction and higher superconducting critical parameter values in films grown on SrTiO3 substrate due to the better lattice matching.
Studies of proximity effect in B(Pb)SCCO and Manganite heterostructures : The Effect of proximity of the charge-ordered antiferromagnetic manganite Pr0.5Ca0.5MnO3 and ferromagnetic Pr0.6Sr0.4MnO3 systems on B(Pb)SCCO in the heterostructural B(Pb)SCCO/ Pr0.5Sr0.5MnO3 and B(Pb)SCCO/ Pr0.6Sr0.4MnO3 thin films has been investigated. Results indicate the detrimental effect on the superconducting critical properties due to the proximity of the magnetic order at the interface. The superconducting upper critical field is observed to more isotropic in the heterostructure films as compared to single layer film due to the proximity of the manganite at the interface. Studies carried out on ultra thin PSMO/PCMO heterostrural thin films revealed an enhanced CMR effect near room temperature due to the interfacial interaction of the manganites.
Studies on Bi2Se3–based 3-D topological insulators (TI) and their proximity with s-wave superconductors : Heterostructures comprising of NbN-Bi2Se3, Nb- Bi2Se3, and MoN- Bi2Se3 were fabricated to study the effect of proximity on the superconducting properties of the 5nm to 100 nm thick superconductors grown on the Topological Insulator film. A large suppression in the critical current has been observed in the films grown on the TI substrate. This is attributed to the large density of weak links in the bilayers.
Establishment of structure-property correlations in double perovskite systems : Influence of octahedral-site cations (B-site) ordering on the magnetic behaviour of double perovskite oxides: La2TiCoO6, Sr2YRuO6, Gd2CuTiO6 and Y2CuTiO6 has been investigated. The compounds with ordering of B-site cations viz., La2TiCoO6, Sr2YRuO6 exhibit antiferromagnetic transition. The disordered Gd2CuTiO6 displays second-order phase transition below 20 K for applied fields above 1.2 T. It has high dielectric constant with low dielectric loss at 300 K and 100 Hz. In contrast to Gd2CuTiO6, hexagonal Y2CuTiO6 compound with Cu and Ti disorders display quantum spin liquid ground state down to 100 mK.
Investigation of Magneto-caloric effect in perovskites and chalcogenide systems: Magnetocaloric effect behaviour has been studied in perovskite systems viz., Sr2YRuO6, La2MnNiO6, YbMnO3, TbMnO3 and in chalcogenide systems viz., Sb substituted MnAs, EuS, EuSe and DySe2.
Systematic high pressure and HP-HT structural stability studies performed on rare earth Uranate systems RE6UO12 (RE – La, Sm, Gd and Dy). The system is found to be stable and thermal expansion coefficient with respect to pressure has been obtained upto 6GPa and 500 C.
The interplay of Boron content, crystal and electronic structures in compressibility behavior of TMxB (TM = Fe, Ni, Co & Mo; x=0.5 to 3) has been studied by carrying out high pressure XRD and first principle electronic structure calculations.
Structural stability studies in nano-U3O8 under variable P-T conditions have been carried out. Enhanced kinetics of the pressure induced structural phase transition is observed.
HP-HT structural phase diagram has been established for the potential detector material Cd0.9Zn0.1Te and a technologically important zeolite.
High pressure synthesis of super hard manganese monocarbide by laser heated diamond anvil cell facility
Pressure induced full fledged superconductivity in BaFe2As2 single crystal reported for the first time and a comprehensive studies on Unification of the Pressure and composition dependence of Superconductivity in Ru substituted BaFe2As2 have been brought out.
Enhanced superconductivity and superconductor to insulator transition in nano-crystalline molybdenum thin films
Observation of superconductivity in SrMnBi2 and Bi interface reported.
Evolution of superconducting properties of coexistent Bi-2212 and Bi-2223 phases in BSCCO high temperature superconductors in bulk as well as thin films yielding maximal Tc ~ 110K
Study of evolution of Normal and Superconducting states of MgCNi3 upon Fe and Co substitution and external pressure
Observance of Superconductivity in Fe1+δSe1-xTex thin films with maximal Tc ~14K
Detailed studies on magnetic and magneto-caloric rare earth based Selenides and manganite revealing large magnetocaloric effect in hexagonal multiferroic Yb1-xHoxMnO3 ; EuSe systems
Role of Se vacancies on Shubnikov deHaas oscillations in Bi2Se3 topological insulator has been comprehensively brought out in a combined magneto-resistance and positron annihilation studies
Observation Quantum coherence phenomenon in disordered Bi2SeTe2 topological single crystal revealing the effect of annealing
High pressure studies on electronic transport properties of Te substituted Bi2Se3-xTex topological insulators revealing multiple pressure induced phase transition from insulator to metal and then metal to superconductor.
Studies on magnetic properties of Cobalt-doped Bi1.9Co0.05 Sb0.05Se3 topological single crystals revealing Shubnikov-de Haas oscillations.
Observations on proximity induced changes of critical field in Mo/Bi1.95Sb0.05Se3 hybrid structure
High pressure studies on RuIn3 single crystal performed and reported for the first time
First report on Pressure Induced Insulator- Metal Transition of Localized States in FeSi1-xGex and quantitative understanding of its pressure dependent behaviour under novel proposed theoretical model.
Observance of Pressure Induced Insulator to Metal Transition in d-electron based kondo insulator FeSb2 and its understanding within our novel model
Thickness dependent electrical resistivity evolution in Fe1-xNixSb2 thin films
Proximity Effects Studies on the hetero-structures of Superconductors, Topological Insulators, Magnetic systems (CMR)
First report on Strain enhanced spin polarization in Nd0.43Sr0.57MnO3/YBa2Cu3O7 bilayres
Modulation of superconductivity by spin canting in a hybrid antiferromagnet/superconductor oxide
Thickness controlled proximity effect studies in C-type antiferromagnet/superconductor heterostructure Nd0.35Sr0.65MnO3/YBa2Cu3O7 demonstrating a dynamic completion between the superconducting pairing and the exchange field leading to re-entrance of the superconductivity for the first time.
A comprehensive investigation on current and magnetic field dependent proximity effects in the Nd0.43Sr0.57MnO3/YBa2Cu3O7 heterostructure
Discovered two new high pressure phases of energetic material TEX (C6H6N4O8: 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane); investigated pressure induced phase transformations in melt-cast explosive dinitroanisole (DNAN), and Bis(3,5-dinitro-4-aminopyrazolyl) methane (BDNAPM)
Discovered new high pressure phases in molecular ferroelectric materials diisopropylammonium bromide (DIPAB), diisopropylammonium perchlorate (DIPAP) and hybrid organic-inorganic 2-D perovskite bis-benzylammonium lead tetrachloride (BALC)
Synthesized novel microgel-hydrogel composite photonic crystals (CPC), monitored and extracted uranyl ions in aqueous solutions using this CPC
Monitored structural and dynamical changes across Tg in network glasses (IPG, B2O3 and TeO2) at different length scales of ordering and correlated structure with property
Discovered elastic anomalies in Ca doped SrTiO3 quantum paraelectrics which was not previously known
Discovered elastic anomalies in ferroelectrics and mapped to phase transitions
Trapped NxN particles in arrays and different geometries using holographic optical tweezers (HOTs)
Tracked the volume phase transition in colloids and investigated PNIPAm structure, dynamics and viscoelasticity in various phases
Raman spectra of uranium metal were recorded (for the first time in the world) using a novel SERS technique, and reported
Development of metal anvil based high pressure and high temperature facility for resistivity studies
High pressure high temperature electrical resistivity on nickel provided evidence for Mott’s conjecture that significant changes occur at Curie temperature
The first high pressure structural stability studies on actinide compounds (UC, ThS and ThSe) were reported
High pressure high temperature electrical resistivity on U & Th indicated that Th becomes less metallic at high pressure
Indigenously developed Mao-Bell type Diamond Anvil Cell (DAC), capable of achieving P ~ 100 GPa
Systematic high pressure structural stability studies on early actinide elements and their intermetallic compounds, lanthanide based intermetallic compounds, transitions metals and their borides, metallic glasses, quasicrystals, fullerenes, rare-earth sesquioxides, pyrochlore systems, etc.
Establishing pressure composition phase diagram of mixed rare earth sequioxides
Setting up of the first Laser Heated Diamond Anvil Cell (LHDAC) facility in the country (P ~ 100 GPa, T ~ 5000 K)
High pressure synthesis of super hard MnC by LHDAC
Setting up of in-situ HPHT micro XRD facility (P ~ 25 GPa, T ~ 1000 K)
In-situ HPHT XRD shows enhanced kinetics of phase transformation in nano U3O8
Expertise
Raman and Brillouin spectroscopy
Holographic optical tweazer
Quantum optics
Soft condensed matters and glasses
Temperature dependent X-ray crystallography of structural, Low temperature & High magnetic
field based study for electronic & magnetic properties as a function of pressure, temperature
Preparation and studies on thin films and hetero-structures comprising of various superconducting, magnetic and topological systems
Indigenously developed Mao-Bell type Diamond Anvil Cell (DAC), capable of achieving P ~ 100 GPa
Design and development of micro heater for HELIOS membrane DAC
Design and development of liquid argon loading facility for loading liquefied argon in DAC
Infrastructure / Facilities
Structural studies at extreme condition of Pressure and Temperature: In-situ High Pressure, High Temperature (HP-HT) XRD facility at BL-12, INDUS-2, RRCAT has been successfully set up, enabling probing of HP – HT structural phase diagram of oxides of Uranium and II-VI compounds, up to 25 GPa and 1000 deg C.?
Development and optimization of Holographic Optical tweezers (HOTs): Holographic Optical tweezers (HOTs) and algorithms were developed to modulate the phase of laser light to generate desired patterns of optical traps. Spatial light modulator (SLM) was optimized for global and spatially varying phase response. A technique for mapping the laser intensity across the SLM was developed enabling creation of aberration-free optical traps. This also allows realization of HOTs with any arbitrary laser beam profile compared to that of traditional Gaussian laser beams used for HOTs.
Development of interferographic method for quantum state reconstruction: A two-photon non-local interferographic method have been designed for reconstruction of the quantum state of polarization-entangled photon pairs generated with type-I spontaneous parametric down conversion. A scheme for quantum state engineering on the Spin-Orbital angular momentum space of light beams for generating desired states using only q-plates and wave-plates has been developed.