Rajib Mondal

UGC-DAE Consortium for Scientific Research · Department of Materials Science

Co-doped MnNiGe1.05 alloys of nominal compositions MnNi1−xCoxGe1.05 (for x=0.075 and 0.125), with a significant amount of vacancies at the transition-metal sites, have been explored through temperature-dependent structural and magnetic investigations. Such studies confirm the presence of martensitic phase transition (MPT) in both the alloys. Howeve...

We investigate thickness-dependent transformation from the paramagnetic to the ferromagnetic phase in Cr2Ge2Te6 (CGT) in bulk and few-layer flake forms. Two-dimensional (2D) Ising-like critical transition in bulk CGT occurs at Tc=67 K with out-of-plane magnetic anisotropy. Few-layer CGT on hBN/SiO2/Si substrate displays the same Tc but also exhibit...

This work reports solvothermal synthesized multiferroic bismuth ferrite nanoparticles (BFO) supported PVDF-HFP membrane (PBF) for the degradation of organic pollutants (Rhodamine B). The bismuth ferrite NPs have been incorporated into the PVDF-HFP matrix in four different concentrations (PBF0, PBF2.5, PBF7.5, PBF11). The BFO perovskite crystals hav...

A comprehensive study of magnetic, room-temperature Mössbauer spectroscopic, room-temperature Raman spectroscopic, magnetocaloric, and critical behavior properties of chemical vapor transport (CVT) grown single-crystalline Fe3−xGeTe2 (x≈0.3) (F3GT) have been performed. The single crystal of F3GT has been formed in a van der Waals force bonded layer...

This work portrays a detailed depiction of degrading two separate carcinogenic organic dyes (Rhodamine B and Eriochrome black T) along with the ablation of pathogenic E. coli bacteria by employing a gadolinium-doped bismuth ferrite (GBF) piezo catalyst. The piezo catalyst has been prepared by a facile two-step solvothermal route and characterized f...

In this work, a low temperature (~600 • C) solution combustion technique is employed for the synthesis of Ni 0.5 Co 0.5 Bi x Fe 2-x O 4 (NCBFO, where x = 0.0, 0.05, 0.1, 0.15, & 0.2) nanoparticles with crystallite size variation of 17-22 nm. The X-ray diffraction (XRD) technique is used to confirm the formation of cubic spinel phase of Bi 3+ doped...

Manipulation of long‐range order in 2D van der Waals (vdW) magnetic materials (e.g., CrI3, CrSiTe3 ,etc.), exfoliated in few‐atomic layer, can be achieved via application of electric field, mechanical‐constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the exposure in the ambient cond...

Manipulation of long-range order in two-dimensional (2D) van der Waals (vdW) magnetic materials (e.g., CrI$_3$, CrSiTe$_3$ etc.), exfoliated in few-atomic layer, can be achieved via application of electric field, mechanical-constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the expos...

Jeanbandyite is one of the rare and unique structured minerals in the perovskite family. Jeanbandyite is a hydroxide perovskite having a formula of (Fe3+1−x, ⎕x) (Sn4+1−y, ⎕y) (OH)6 (⎕ = vacancy). Herein we report for first time the synthesis of jeanbandyite with superparamagnetic properties. The novel FeSnO(OH)5 compound is synthesized by a coprec...

Anisotropic transport, Shubnikov-de Haas (SdH), and de Haas-van Alphen (dHvA) quantum oscillations studies are reported on a high-quality CoSi single crystal grown by the Czochralski method. Temperature-dependent resistivities indicate the dominating electron-electron scattering. Magnetoresistance (MR) at 2 K reaches 610% for I ‖ [111] and B ‖ [01-...

We studied the behavior of nontrivial Dirac fermion states in the antiferromagnetic metal SmBi using angle-resolved photoemission spectroscopy (ARPES). The experimental results exhibit multiple Fermi pockets around the Γ¯ and M¯ points along with a band inversion in the spectrum along the Γ¯−M¯ line consistent with the density functional theory res...

We studied the behavior of nontrivial Dirac fermion states in the antiferromagnetic metal SmBi using angle-resolved photoemission spectroscopy (ARPES). The experimental results exhibit multiple Fermi pockets around the and M points along with a band inversion in the spectrum along theM line consistent with the density functional theory results. In...

Anisotropic transport, Shubnikov-de Haas (SdH), and de Haas-van Alphen (dHvA) quantum oscillations studies are reported on a high-quality CoSi single crystal grown by the Czochralski method. Temperature-dependent resistivities indicate the dominating electron-electron scattering. Magnetoresistance (MR) at 2 K reaches 610% for I||[111] and B||[01-1]...

Single crystals of Ce2Re3Si5 and Pr2Re3Si5 have been grown by the Czochralski method in a tetra-arc furnace. Powder x-ray diffraction confirmed that these compounds crystallize in the U2Mn3Si5-type tetragonal crystal structure with space group P4/mnc (no. 128). The anisotropic physical properties have been studied comprehensively by measuring the m...

We study the electronic structure of a superconducting composition of 122-type Fe-based pnictide material, CaFe 1.9 Co 0.1 As 2 employing high resolution angle resolved photoemission spectroscopy technique. The experimental results exhibit three bands close to Fermi level at Γ-point of the Brillouin zone among which only one band crosses the Fermi...

Low-dimensional layered materials manifest an inherent tendency towards the formation of symmetry reduced charge density wave (CDW) states with exotic properties. Here, we elucidate the anisotropic transport prop- erties of CaCu4As2, which crystallizes in a rhombohedral lattice. Temperature-dependent single-crystal x-ray diffraction in conjunction...

Quantum oscillations in both linear and Hall resistivities and weak antilocalization (WAL) are barely observed in bulk single crystals. Here we report the transport properties of a CaCuSb single crystal that crystallizes in the hexagonal crystal structure. The magnetotransport studies reveal WAL and Shubnikov−de Haas (SdH) quantum oscillations with...

Quantum oscillations in both linear and Hall resistivities and weak antilocalization (WAL) are barely observed in bulk single crystals. Here we report the transport properties of a CaCuSb single crystal that crystallizes in the hexagonal crystal structure. The magnetotransport studies reveal WAL and Shubnikov-de Haas (SdH) quantum oscillations with...

We report on the fabrication of nano-devices on the \hkl[-1 0 1] surface of a Weyl semimetal, a macroscopic crystal of TaAs, and low-temperature transport measurements. We can implement electron beam lithography by peeling off and transferring the resist for nanofabrication onto the irregular crystal. We fabricate the device electrodes with superco...

We report on the fabrication of nano-devices on the [1¯01] surface of a Weyl semimetal, a macroscopic crystal of TaAs, and low-temperature transport measurements. We can implement electron beam lithography by peeling off and transferring the resist for nanofabrication onto the irregular crystal. We fabricate the device electrodes with superconducti...

We studied the behavior of Dirac Fermions in an antiferromagnetic metal, SmBi using angle-resolved photoemission spectroscopy (ARPES). The experimental results exhibit two hole pockets around $\overline{\Gamma}$-point, an electron pocket around $\overline{M}$-point and band inversion along $\overline{\Gamma}$-$\overline{M}$ line consistent with the...

Coupling among conduction electrons (e.g. Zhang-Rice singlet) are often manifested in the core level spectra of exotic materials such as cuprate superconductors, manganites, etc. These states are believed to play key roles in the ground state properties and appear as low binding energy features. To explore such possibilities in the Fe-based systems...

Coupling among conduction electrons (e.g., Zhang-Rice singlet) are often manifested in the core level spectra of exotic materials such as cuprate superconductors, manganites, etc. These states are believed to play key roles in the ground state properties and appear as low binding energy features. To explore such possibilities in the Fe-based system...

We investigate the evolution of the local structural parameters and their implication in unconventional superconductivity of 122 class of materials employing extended x-ray absorption fine structure studies. The spectral functions near the Fe K- and As K-absorption edges of CaFe2As2 and its superconducting composition, CaFe1.9Co0.1As2 (Tc = 12 K) e...

The effect of Dy doping on CaMnO3 (CDMO) has been thoroughly investigated. The room-temperature structure, low-temperature magnetic transitions, and high-temperature electrical properties of CDMO were studied using X-ray diffraction, magnetization, and dielectric techniques. The CDMO exhibits an orthorhombic structure with Pnma symmetry. The low-te...

We report on the observation of a nonsaturating, extremely large magnetoresistance (XMR) and the Fermi surface topology of a high quality WSi2 single crystal grown by the Czochralski method. The magnetoresistance at T=2K reaches a value ≈105% in 14 T magnetic field with no sign of saturation. The Hall resistivity data of WSi2 was found to be highly...

We report on the single crystal growth and transport properties of a topological semimetal CaAgBi which crystallizes in the hexagonalABC-type structure with the non-centrosymmetric space groupP63mc(No. 186). The transverse magnetoresistance measurements with current in the basal plane of the hexagonal crystal structure reveal a value of about 30 %...

Quantum transitions in Fe-based systems are believed to involve spin, charge and nematic fluctuations. Complex structural phase diagram in these materials often emphasizes importance of covalency in their exotic properties, which is directly linked to the local structural network and barely understood. In order to address this outstanding issue, we...

The recently proposed novel materials class called Weyl-Kondo semimetal (WKSM) is a time reversal invariant but inversion symmetry broken Kondo semimetal in which Weyl nodes are pushed to the Fermi level by the Kondo interaction. Here we explore whether CeCu$_{1+x}$As$_2$ may be a new WKSM candidate. We report on its single-crystal growth, structur...

We report on the single crystal growth and transport properties of a topological semimetal CaAgBi which crystallises in the hexagonal $ABC-$type structure with the non-centrosymmetric space group $\mathit{P6_3mc}$ (No. 186). The transverse magnetoresistance measurements with current in the basal plane of the hexagonal crystal structure reveal a val...

The present article reports the governing influence of substituting the M²⁺ site in nanoscale MFe2O4 spinel ferrites by different magnetic metals (Fe/Mn/Co/Ni) on magnetorheological and magneto-elastoviscous behaviors of the corresponding magnetorheological fluids (MRFs). Different doped MFe2O4 nanoparticles have been synthesized using the polyol-a...

We report a comprehensive study of the growth of GaN layers on (1 0 0)-oriented Ga2O3 substrates by metalorganic vapour phase epitaxy (MOVPE), especially the improvement on using an intermediate facet-control layer between the low-temperature buffer and the high-temperature GaN layer compared to the usual two-step growth process. We examined in det...

β-Ga2O3 is a promising wide-bandgap semiconductor material for power electronic applications and as a conducting substrate for GaN growth. In this work, we report the growth of high quality single crystal β-Ga2O3 by the optical floating zone technique. A detailed study of the effect of gas ambient on the quality of Ga2O3 single crystals was carried...

The present article reports the governing influence of substituting the M2 site in nanoscale MFe2O4 spinel ferrites by different magnetic metals Fe,Mn,Co,Ni on magnetorheological and magneto elastoviscous behaviors of the corresponding magnetorheological fluids MRFs. Different doped MFe2O4 nanoparticles have been synthesized using the polyol assist...

Magnetic and magnetocaloric properties of the single crystalline Cr 5 Te 8 have been studied. Temperature dependent dc and ac magnetization of Cr 5 Te 8 , upon cooling, reveals a paramagnetic to ferromagnetic transition at ≈ 220 K (T C ). Field dependent magnetization in the ordered state at 2 K reveals strong anisotropy with c-axis as the easy axi...

Polycrystalline DyxSr2-xTiMnO6 (x = 0, 0.5) double perovskite oxides crystallize in cubic structure (Space group Fm-3m, No. 225) at room temperature. The oxide Sr2TiMnO6 orders antiferromagnetically at ∼14 K (TN) below which zero-field-cooled and field-cooled magnetization data show bifurcation. Magnetization of the sample Dy0.5Sr1.5TiMnO6 shows on...

We report on the single-crystal growth and anisotropic physical properties of CeAgAs2. The compound crystallizes as an ordered variant of the HfCuSi2-type crystal structure and adopts the orthorhombic space group Pmca (No. 57) with two symmetry-inequivalent cerium atomic positions in the unit cell. The orthorhombic crystal structure of the single c...

We report on the single crystal growth and anisotropic physical properties of CeAgAs$_2$. The compound crystallizes as on ordered variant of the HfCuSi$_2$-type crystal structure and adopts the orthorhombic space group $Pmca$~(\#57) with two symmetry inequivalent cerium atomic positions in the unit cell. The orthorhombic crystal structure of our si...

We have grown a single crystal of HoAl2Ge2, which crystallizes in the hexagonal CaAl2Si2 type structure with Ho ions in the trigonal coordination in the ab plane. The data obtained from the bulk measurement techniques of magnetization, heat capacity and transport reveal that HoAl2Ge2 orders antiferromagnetically at TN ∼6.5 K. The susceptibility bel...

The magnetoresistance is the magnetic field induced change of electrical resistivity of a material. Recent studies have revealed extremely large magnetoresistance in several non-magnetic semimetals, which has been explained on the basis of either electron-hole compensation or the Fermi surface topology, or the combination of both. Here, we present...

The temperature dependence of resistivity ρ(T) of a polycrystalline sample and a single crystal sample (current along the [0001] direction) of α - Titanium (Ti) at low temperatures is revisited to understand the electrical charge transport phenomena in this hexagonal closed pack metal. We show that the ρ(T) in single crystal Ti can be explained by...

Magnetic and magnetocaloric properties of cubic Laves phase rare-earth intermetallic HoCo0.25Ni1.75 compound have been investigated. Magnetization measurements show that HoCo0.25Ni1.75 orders ferromagnetically at 22 K (TC). The magnetization vs field (M-H) isotherm at 2 K shows negligible hysteresis. The isothermal magnetic entropy change (ΔSm) is...

Magnetic and magnetocaloric properties of polycrystalline rare earth intermetallic compounds HoCo2-xNix (x=0.75 and 1.25) have been investigated. Both HoCo1.25Ni0.75 and HoCo0.75Ni1.25 compounds crystallize in MgCu2 type, cubic Laves phase structure (space group Fd (3) over barm, no. 227) and order ferromagnetically at similar to 40 K and similar t...

Magnetic and magnetocaloric properties of cubic Laves phase RCoNi (R = Gd, Tb, Dy, and Ho) compounds have been studied. The RCoNi (R = Gd, Tb, Dy, and Ho) compounds order ferromagnetically at ∼200 K, ∼113 K, ∼68 K, and ∼42 K (TC), respectively. Field dependent magnetization data of RCoNi at 5 K in fields up to 7 T reveal saturation behaviour with m...

Nanocrystalline La0.15Ca0.85MnO3 samples of various grain sizes ranging from ∼17 to 42 nm have been prepared by sol-gel technique. Phase purity and composition were verified by room temperature x-ray diffraction and SEM-EDAX analysis. The bulk La0.15Ca0.85MnO3 is known to order antiferromagnetically around 170 K and to undergo a simultaneous crysta...

Magnetic and magnetocaloric properties of Laves phase rare earth intermetallic compound DyCoNi (cubic, MgCu2-type) have been studied. Magnetization data reveal a ferromagnetic transition at ∼68 K (TC). Magnetocaloric effect has been estimated in terms isothermal magnetic entropy change using field dependent magnetization data taken at various temp...

Magnetic properties of the double perovskite oxide, Sr2TiMnO6, have been studied by means of bulk magnetization and powder neutron diffraction experiments. Low field magnetization data reveal transitions at similar to 45 K (T-C) and at similar to 15 K (T-N). A magnetic moment value of only similar to 0.23 mu(B)/F.U. is attained at 5 K in the 7 T fi...