A5056090583- Iron-based superconductors research
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Institute of High Pressure Physics
2021-2024
Polish Academy of Sciences
2021-2024
University of Oxford
2018-2023
Muroran Institute of Technology
2016-2017
Leibniz Institute for Solid State and Materials Research
2010-2016
Aoyama Gakuin University
2016
The University of Tokyo
2013-2015
Leibniz Association
2011-2015
Jawaharlal Nehru University
2009-2013
Indian Institute of Science Education and Research Pune
2010-2012
We have studied the interplay of magnetism and superconductivity in ${\text{LaFeAsO}}_{1\ensuremath{-}x}{\text{F}}_{x}$ $\text{Ca}{({\text{Fe}}_{1\ensuremath{-}x}{\text{Co}}_{x})}_{2}{\text{As}}_{2}$. While antiferromagnetic spin-density wave formation is suppressed evolves, all samples show a doping-independent strong increase normal-state susceptibility upon heating which appears general feature iron pnictides. The data provide evidence for robust local correlations persisting even...
We present a comprehensive study of the critical current densities and superconducting vortex phase diagram in stoichiometric superconductor ${\mathrm{CaKFe}}_{4}{\mathrm{As}}_{4}$ which has temperature $\ensuremath{\sim}35\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. performed detailed magnetization measurements both high quality single crystals for different orientations an applied magnetic field up to 16 T powder sample. find extremely large density, ${J}_{c}$,...
Platelet-like single crystals of the Ca(Fe1-xCox)2As2 series having lateral dimensions up to 15 mm and thickness 0.5 were obtained from high temperature solution growth technique using Sn flux. Upon Co doping, c-axis tetragonal unit cell decreases, while a-axis shows a less significant variation. Pristine CaFe2As2 combined spin-density-wave structural transition near T = 166 K which gradually shifts lower temperatures splits with increasing Co-doping. Both transitions terminate abruptly at...
A series of FeSe0.5Te0.5 bulk samples have been prepared through the high gas pressure and high-temperature synthesis (HP-HTS) method to optimize growth conditions, for first time investigated their superconducting properties using structural, microstructure, transport, magnetic measurements reach final conclusions. Ex-situ in-situ processes are used prepare under a range pressures Ta-tube without Tatube. The parent compound synthesized by convenient at ambient (CSP) exhibits transition...
The authors investigate the normal transport of superconducting FeSe1-xSx across a nematic phase transition using high magnetic fields up to 69 T establish temperature and field-dependencies. They find that low magnetotransport electronic state is unique it significantly influenced by changes occur in structure scattering with lattice spin fluctuations transition.
AeAFe4As4 (Ae = Ca, A K; 1144) having a transition temperature of 35 K is stoichiometric family iron-based superconductors (FBS). Here, we present detailed study high-pressure synthesis CaKFe4As4 bulks to investigate the impact these conditions on superconducting properties 1144 family. Additionally, samples are also prepared by conventional method at ambient pressure (CSP) and studied influence impurities CaKFe4As4. Structural, microstructural, transport magnetization measurements have been...
A systematic investigation has been performed by synthesis and comprehensive characterization of a series SmFe1-xCuxAsO0.8F0.2 bulks (x = 0 to 0.2). These samples are well characterized structural, Raman spectroscopy, microstructural, transport, magnetic measurements, supplementary calculations within density functional theory (DFT). The parent compound, SmFeAsO0.8F0.2 (Sm1111), exhibits superconducting transition temperature (Tc) approximately 54 K. lattice volume (V) is increased with Cu...
Low-temperature synthesis is a promising and potentially effective method for improving superconducting properties. We report on the fabrication of polycrystalline samples SmFeAsO1-xFx with nominal x content varying in wide range = 0-0.35 synthesized at 900 deg C. This temperature around 300 C lower than conventional temperature. The variation lattice parameters transition (Tc) various F-doped indicates that reduction unit cell volume (V) seems to be main reason rise Tc up 57.8 K....
The enhanced performance of superconducting FeSe0.5Te0.5 materials with added microsized Pb and Sn particles is presented. A series (FeSe0.5Te0.5 + xPb ySn; x = y 0-0.1) bulks are fabricated by solid-state reaction method characterized through various measurements. very small amount additions enhance the transition temperature (Tconset) pure 1 K, sharpening improving metallic nature in normal state, whereas larger metal reduce Tconset broadening transition. Microstructural analysis transport...
CaKFe4As4 (1144) is a unique stoichiometric iron-based superconductor which harbors high upper critical fields and large current densities. In this work, we describe study to optimize the synthesis conditions of polycrystalline samples assess their structural, magnetic transport properties. The were prepared over wide temperature range (900 °C–1100 °C) pure phase formation centered around 955 °C. Outside region, impurity phases KFe2As2 CaFe2As2 can also form. Magnetic susceptibility...
The discovery of iron-based superconductors (FBS) and their superconducting properties has generated huge research interest provided a very rich physics high Tc family for fundamental experimental studies. 1111 (REFeAsO, RE = Rare earth) 1144 (AEAFe4As4, AE Ca, Eu; A K, Rb) families are the two most important FBS, which offer 58 K 36 with doping without doping, respectively. Furthermore, crystal growth these is not an easy process, lot efforts have been reported in this direction. However,...
The high-pressure growth technique generally plays an important role in the improvement of sample quality and enhancement various physical magnetic properties materials. high gas pressure provides a large space (10–15 cm) to grow kinds In this paper, we introduce high-temperature synthesis (HP-HTS) that is present at our institute applied process different superconducting materials, particularly iron-based superconductors. More details working principle HP-HTS are discussed. We have also...
We investigate the critical current density and vortex dynamics in single crystals of Ca(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ ($x$ = 0.051, 0.056, 0.065, 0.073). The samples exhibit different temperatures superconducting phase fractions. show that contrast to their Ba-based counterpart, do not a second peak field dependence magnetization. calculated composition-dependent ($j_{\rm c}$) increases initially with Co doping, maximizing at $x$ then decreases. This variation $j_{\rm c}$ follows fractions...
Non-magnetic impurities in iron-based superconductors can provide an important tool to understand the pair symmetry and they influence significantly transport superconducting behaviour. Here, we present a study of role strong impurity potential Fe plane, induced by Cu substitution, on electronic properties single crystals FeSe. The addition quickly suppresses both nematic states, increases residual resistivity due enhanced scattering. Using magnetotransport data up 35 T for small amount...
A series of polycrystalline SmFeAsO1−xFx bulks (x = 0–0.25) were synthesized by a one step solid state reaction method at low heat temperature 900 ° C, which was about 300 C lower than the conventional (∼1200 C). The magnetic susceptibility measurements showed single superconducting transitions for lightly doped samples with 0.05 ≤ x 0.12, while double-step-like observed in ≥ 0.15, indicating weak-link behavior grains. double transition is due to possible occurrence intergranular (at...
We report the synthesis and characterization of a new electron-doped La-oxypnictide superconductor by partial substitution lanthanum thorium. The superconducting transition temperature at about 30.3 K was observed in La(0.8)Th(0.2)FeAsO, which is highest La-based oxypnictide superconductors synthesized ambient pressure. find that decrease lattice parameters with Th doping LaOFeAs more drastic as compared to obtained high pressure (6 GPa) oxygen-deficient LaOFeAs. resistivity magnetic...
We report the synthesis and characterization of antimony-doped oxypnictide superconductor, LaO0.8F0.2FeAs1−xSbx (x = 0.05 0.10). The parent compound LaOFeAs with fluorine doping exhibits superconductivity at maximum transition temperature ∼28.5 K (at ambient pressure). Here we partially substitute As by Sb (LaO0.8F0.2FeAs1−xSbx) observe enhancement to 30.1 K. This is one rare case where Tc increases in conducting layer (FeAs) this leads highest any La-based oxypnictide. X-ray diffraction...
We report $^{75}$As NQR measurements on single crystalline Ca(Fe$_{1-x}$Co$_x$)$_2$As$_2$ ($0\leq x \leq 0.09$). The nuclear spin-lattice relaxation rate $T_1^{-1}$ as a function of temperature $T$ and Co dopant concentration $x$ reveals normal-state pseudogap-like phase below crossover $T^*$ in the under- optimally-doped region. resulting $x$-$T$ diagram shows that, after suppression spin-density-wave order, intersects $T_c$ falling to zero rapidly near optimal doping regime. Possible...