The effect of Ni and Fe doping on Hall anomaly in vortex state of doped YBCO samples
M
Nazarzadeh
دانشگاه الزهرا
author
F
Saeb
دانشگاه الزهرا
author
V
Daadmehr
دانشگاه الزهرا
author
text
article
2019
per
We have investigated hall effect on YBa2Cu3-xMxO7-δ (M=Ni, Fe) bulk samples, with dopant amount 0 ≤ x ≤ 0.045 for Ni and 0 ≤ x ≤ 0.03 for Fe, with magnetic field (H=2.52, 4.61, 6.27 kOe) perpendicular to sample’s surface with constant current 100 mA. Our study shows that as both dopants increases, TC decreases and it decreases faster by Ni . In these ranges of dopant and magnetic field the Hall sign reversal has been observed in all samples once and also ∆max has occurred in lower temperatures, its magnitude increases by Ni, and in Fe doped samples except in sample with dopant amount x=0.03, which almost decreases, that it can show effect of magnetic doping on hall effect.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
73
76
http://ijpr.iut.ac.ir/article_855_6c6b88d3f6e83715f8d19774786cfdbc.pdf
The effect of Ba substitution at Sr site in Bi-2223 high-TC superconductors
H
Salamati
author
T
Morshedloo
author
P
Kameli
author
M
Baghi
author
H
Ahmadvand
author
E
Abdolhosseini
author
D
Sohrabi
author
text
article
2019
per
Bi1.8Pb0.4Sr2-xBaxCa2.2Cu3Oy (x-0, 0.1, 0.2, 0.3) samples were prepared by a conventional solid state reaction method. The effect of Ba substitution at Sr site in Bi-2223 high-TC superconductors have been investigated by the XRD, SEM, dc electrical resistivity and ac susceptibility. XRD and SEM analysis indicated Ba substitution decreased temperature of 2223 phase formation. The highest 2223 phase fraction was obtained for the sample with x=0.1 (A1 sample). This phase decreased by increasing Ba concentration (x>0.1). Ba doping up to x=0.1 decreased impurity phases but doping more than 0.1 increased. Dc electrical resistivity data and ac susceptibility measurements showed the transition temperature of grains and grain boundaries (Tc , Tcj ) increased and the transition width (ΔTc ) decreased for A1 sample. This behavior can be described by decreasing impurity phases and increasing 2223 phase. Flux pinning force and intergranular critical current densities (Jcm ) of A1 sample increased. It was suggested it is because of a small precipitation of Ba in grain boundaries as effective pinning centers. Ba doping more than 0.1 reduced the intergranular coupling and increased weak link behavior by increasing impurity phases. It decreased Tcj , Jcm and flux pinning force.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
77
81
http://ijpr.iut.ac.ir/article_856_26646a74577f4c80f0534eeccf588e0f.pdf
Hall effect in CNT doped YBCO high temperature superconductor
S
Dadras
دانشگاه الزهرا
author
N
Manivannan2
author
KH
Kim
author
V
Daadmehr
دانشگاه الزهرا
author
text
article
2019
per
In order to study Hall effect in pure and CNT doped YBCO polycrystalline samples, we have measured longitudinal and transverse voltages at the different magnetic field (0-9T) in the vortex state. We found a sign reversal for pure sample near 3T and double sign reversal of the Hall coefficient for CNT doped sample near 3 and 5T. It can be deduced that CNT doping caused strong flux pinning and Hall double sign reversal in this compound.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
83
86
http://ijpr.iut.ac.ir/article_857_b58f2a4576d9ad772778e8b95396ac95.pdf
Magnetic and structure properties of Cd doping Bi-2223 superconductor
SE
Mousavi Ghahfarokhi
author
M
Zargar Shoushtari
author
text
article
2019
per
In this paper, Bi1.64-xPb0.36CdxSr2Ca2Cu3Oy (BPCSCCO) superconductor with x = 0.0, 0.02, 0.04 and 0.06 is made by the solid state reaction method. The magnetic susceptibility measurements were performed using AC susceptometer. The microstructure and morphology of the samples have been studied by X-ray diffraction, scanning electron microscope and energy dispersive X-ray. The results show that the partial substitution of Pb for Bi in the Bi-based superconductor increases the volume fraction of Bi-2223 phase. We also found that by doping of Cd, the high Tc phase is promoted and stabilized in the Bi-Pb-Sr-Ca-Cu-O system. The results of the X-Ray diffraction patterns and magnetic susceptibility measurements show that the low amount of Cd and long annealing time enhance the fraction of Bi-2223 phase. The maximum value volume fraction of Bi-2223 phase for sample with annealing time of 270 hours and 0.04 of Cd doping is obtained
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
87
90
http://ijpr.iut.ac.ir/article_858_fd361fe13ae8a20dfb98ea6ab681a7aa.pdf
Flux dynamics in Y3Ba5Cu8O18 superconductor
A
Aliabadi
author
Y
Akhavan-Farshchi
author
M
Akhavan
author
text
article
2019
per
We have studied the thermally activated flux creep of a newly fabricated superconductor Y3Ba5Cu8O18 with the superconducting transition temperature 102 K. Analysis of the transition spread from the normal state to superconducting state in the electrical resistivity revealed that the thermally activated flux creep explains the electron share in the vicinity of the transition temperature Tc. The activation energy U in a magnetic field below 15 kOe has been calculated by the corrected thermally activated flux creep model, and the pinning energy is exponentially related to the magnetic field.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
91
94
http://ijpr.iut.ac.ir/article_859_16eab37aa9702432422c83db9c087b14.pdf
Structure and properties of YBa2Cu3O7-Î´ superconductor doped with bulk cadmium oxide
A
Echresh
دانشگاه شهید چمران اهواز
author
M
Zargar Shoushtari
author
M
Farbod
دانشگاه شهید چمران اهواز
author
text
article
2019
per
In this paper, the Y1-xCdxBa2Cu3O7-δ superconductor with x=0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5 are prepared using the solid state method and the structure, electrical resistance, critical current density and critical temperature of it, have been studied. The results show that these doping do not affect so much on the structure and lattice parameters. The electrical resistance of samples increased with doping. A little amount of doping cadmium improve critical current density such that the sample x=0.1 has a maximum critical current density among the samples. The critical temperature with doping cadmium up to x=0.2 has little fluctuation and its variation can be ignored, but by increasing up to x=0.5 the critical temperature decreases gradually.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
95
99
http://ijpr.iut.ac.ir/article_860_f4f9c53de8a6b23876b5c5b46e48a061.pdf
Preparation of YBCO superconductor nanoparticles by sol-gel combustion method
M
Farbod
دانشگاه شهید چمران اهواز
author
M
Tayeb Taher
author
I
Kazeminezhad
author
text
article
2019
per
This paper describes the details of synthesizing nano crystalline YBCO superconductor using a sol-gel combustion method and the effect of sol pH and sintering temperature on particle size was investigated. The sintering temperature was chosen 880°C and the samples were annealed at this temperature for 5 hours. The morphology and structure of the nano scale products were characterized by powder X-ray diffraction and scanning electron microscopy. The results showed the samples prepared using the sol with pH of 5 and 7 have mean particle size of 500 and 200 nm, respectively. In order to investigate the effect of sintering temperature on the size of YBCO particles three sets of samples from the sol with pH of 7 were sintered at 800, 880 and 950°C. The results showed the samples sintered at 800, 880 and 950°C have the average particle size of 100, 200 and 400 nm respectively.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
101
105
http://ijpr.iut.ac.ir/article_861_1c039128b969d6bbd302ceab9bc297c8.pdf
Fulx-pinning mechanism and activation energy in malic acid-doped MgB2
SR
Ghorbani
author
M
Bashi
author
A
Broghani
author
text
article
2019
per
Fulx-pinning mechanism and activation energy of MgB2 doped with 10 wt % malic- acid has been investigated by measurement of critical current density and resistivity as a function of magnetic fields and temperatures. The field dependence of the critical current density, Jc(B), was analyzed within the collective pinning model. A crossover field, Bsb, from the single vortex to the small vortex bundle-pinning regime was observed. For sintered sample, the temperature dependence of Bsb(T) at low temperature is in good agreement with the δℓ pinning mechanism, i.e., pinning associated with charge-carrier mean free path fluctuation. The activation energy was decreased linearly by increasing magnetic field.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
107
111
http://ijpr.iut.ac.ir/article_862_e8bb821af20b49ab1c625a30a15872f3.pdf
The magnetization and the critical current density in NdO0.82F0.18FeAs superconductor
SR
Ghorbani
author
XL
Wang
دانشگاه ولونگونگ استرالیا
author
text
article
2019
per
The magnetization and the critical current density of newly discovered NdO0.82F0.18FeAs superconductor with a critical temperature, Tc,, of 51.5 K has been studied as a function of applied magnetic field and temperature. It was found that this compound exhibits a standard superconductivity with diamagnetic onset close to Tc at a very low applied magnetic field. It was shown that there was a strong paramagnetic behavior at applied magnetic larger than 50 kOe. This behavior is clearly shown in magnetization curves as a function of applied magnetic field.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
113
116
http://ijpr.iut.ac.ir/article_863_e55d4bf3c131a16f51176266ca1e69d4.pdf
Softening of high energy phonons by insulator-superconductor transition in Ba1-xKxBiO3 system
H
Khosroabadi
author
J
Kobayashi
author
K
Tanaka
author
SH
Miyasaka
author
S
Tajima
author
H
Uchiyama
author
A
Baron
هیوگو ژاپن
author
text
article
2019
per
Single crystals of Ba1-xKxBiO3 compound for 0 < x
Iranian Journal of Physics Research
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1682-6957
10
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2
no.
2019
117
120
http://ijpr.iut.ac.ir/article_864_abcf3a749480d5a784a07a992971f71b.pdf
Effects of anisotropic potentials on the energy gap of Bose gas
F
Nabipoor
دانشگاه اصفهان
author
A
Shahzamanian
author
text
article
2019
per
We investigate the effect of dipole-dipole and quadrapole- quadrapole interaction of a weakly interacting Bose gas near the transition temperature on the energy spectra of the thermal and condensate parts. We use the two fluid model and mean field approximation. We show that the effects of the condensate part on the shift of energy is greater than the case of contact potential
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
121
124
http://ijpr.iut.ac.ir/article_865_cd3b6ab77a4a44a047bc09b7df75096d.pdf
Study of some electronics properties of new superconductor Sr2VO3FeAs in ground state
M
Majidiyan
دانشگاه تربیت معلم سبزوار
author
M
Jami
author
J
Baedi
author
M
Hosseini
author
A
Boroughani
author
text
article
2019
per
In this paper, some electronics properties of new superconductor Sr2VO3FeAs, such as density of states, band structure, density of electron cloud and bound lengths in the ground state have been calculated. According to N(Ef) in ground state CV/T value has been estimated. The calculations were performed in the framework of density functional theory (DFT), using the full potential linearized augmented plane wave (FP-LAPW) method with the general gradient approximation (GGA).
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
125
129
http://ijpr.iut.ac.ir/article_866_0e8e1468f073799a93e23bddbc35b4f0.pdf
Anisotropic peak broadening analysis of SRS diffraction from twin microstructurs in YBCO sample
B
Khoshnevisan
author
M
Mohammadi
author
text
article
2019
per
Reitveld full profile refinement analysis has been done on Synchrotron diffraction data from a powder sample of YBCOx at RT and 500°C. Anisotropic peak broadening for (h00) and (hh0) lines has been observed by Williamson-Hall (W-H) analysis and that is in agreement with formation of twin's microstructures along (110) crystal planes in the sample. In addition, size and strain of the crystallites has been inferred in our study also.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
131
134
http://ijpr.iut.ac.ir/article_867_5cec1f2fd887bf4dbbcf1eaa6f32f55a.pdf
Coherent quantum trasport in ferromagnet-superconductor-ferromagnet graphene junctions
M
Salehi
author
GH
Rashedi
author
text
article
2019
per
In this paper, we investigate the coherent quantum transport in grapheme-based ferromagnet-superconductor-ferromagent junctions within the framework of BCS theory using DBdG quasiparticles equation .The coherency with the finite size of superconductor region has two characteristic features subgap electron transport and oscillations of differential conductance. we show that periodic vanishing of the Andreev reflection at the energies called geometrical resonances above the superconducting gap is a striking consequence of quasiparticles interference. We suggest to make devices that produce polarized spin-current with possible applications in spintronics.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
135
139
http://ijpr.iut.ac.ir/article_868_8e4a5a07be2dd0f5d3c026ae29316fe6.pdf
Charge and spin currents in normal metal sandwiched by tow p-wave
Y
Rahnavard
دانشگاه اصفهان
author
GH
Rashedi
author
text
article
2019
per
Charge and spin transport properties of a clean $SNS$ Josephson junction (triplet superconductor-normal metal-triplet superconductor) are studied using the quasiclassical Eilenberger equation of Green’s function. Our system consists of two p-wave superconducting crystals separated by a Copper nano layer. Effects of thickness of normal layer between superconductors on the spin and charge currents are investigated. Also misorientation between triplet superconductors which creates the spin current is another subject of this paper.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
141
144
http://ijpr.iut.ac.ir/article_869_ba2ac4b244925b62d01f679b37c6f6e6.pdf
Ab-initio calculations of pressure effect on electronic and magnetic structure of ferromagnetic-superconductor RuSr2GdCu2O8
S
Fallahi
author
M
Akhavan
author
text
article
2019
per
We have performed a first-principle calculation of electronic structure of RuSr2GdCu2O8, a ferromagnetic-superconductor, by employing a full-potential linearized augmented plane-wave method within the density functional theory. Hydrostatic pressure applied up to 6 GPa by varying the volume of the unit cell with constant a:b:c ratio. Optimization of internal parameters showed that there exists shear stress due to the residual forces in Ru-O layers which leads to anti-phase rotation of RuO6 octahedra in experimental structure of this compound. Partial charge analysis showed that applying pressure leads to hole injection in Cu-O sheets and by applying charge transfer model, we obtained 1.9 K/GPa for the rate of increase in superconducting transition temperature with pressure. The exchange coupling interaction J between the adjacent Ru atoms was calculated by energy difference between the AFM and FM configuration of magnetic structure of Ru atoms. According to the result of the calculations, the magnetic moment of Ru atoms decreased and exchange coupling parameter J increased by applying pressure.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
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2
no.
2019
145
149
http://ijpr.iut.ac.ir/article_870_1f22b4288130c05b2cae038d227fd670.pdf
Josephson spin-current in superconductor-ferromagnetic-superconductor junctions with singlet superconducting leads
محمد
علیدوست
دانشگاه اصفهان
author
غلامرضا
راشدی
author
text
article
2019
per
We study numerically the electronic heat capacity, spin and charge current in a diffusive Superconductor-Ferromagnetic-Superconductor systems، with singlet superconducting leads and non-uniform ferromagnetic layer. Specially, we focus on ferromagnetic layer with domain wall and conical structures incorporation the spin-active interfaces. We investigate, how the 0-π transition is influenced by non-uniform magnetization texture and also the appearance of spin-current in such structures. We find that for ferromagnetic layer with domain wall structure, only the one component of spin-current is non-zero and for conical structure, three components of spin-current are non-zero. Also we find that specific heat of such junctions can be tuned by changing the superconducting phase difference. Interestingly, spin-current shows a discontinuous jump at the 0-π transition points of the critical charge current.
Iranian Journal of Physics Research
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1682-6957
10
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2
no.
2019
151
154
http://ijpr.iut.ac.ir/article_871_62af1c1dd52723df81ddf6ca9af593b4.pdf
Study of correlation and autocorrelation of supercurrent and charge in stacked Josephson junctions
M
Hamdipour
author
Y
Shukrinov
author
MR
Kolahchi
author
text
article
2019
per
Charge creation in superconductor layers affects current–voltage characteristics (CVC) of the Josephson junction array and creates a breakpoint region in CVC. This charge may oscillate in the form of longitudinal plasma wave, (LPW), or nonregularity. In this paper we intend to distinguish the region with LPW from the nonregular region.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
155
158
http://ijpr.iut.ac.ir/article_872_d94ec4eb89ef0da4fe7a8c0450eb6436.pdf
Correlation level in superconducting Sr2RuO4 system studied by ab-initio LSDA & LSDA+U calculations
Z
Hooshmand
author
H
Hadipour
author
M
Akhavan
author
text
article
2019
per
We have calculated the electronic structure of Sr2RuO4 using the full potential linearized augmented plane wave method in the spin polarized local density approximation. By this calculation, we identify the contribution of different electronic states near Fermi surface and study some electronic parameters like crystal electric field, exchange splitting, and hybridization between different atoms. Calculations are performed in two different approaches: LSDA and LSDA+U. By applying U, we have aimed to measure the electrons correlation near Fermi surface. Thereupon, we will answer if this system realm on the correlated systems region or not?
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
159
163
http://ijpr.iut.ac.ir/article_873_1faf2dd95803e90e04252f50511e17f4.pdf
Role of the lattice dynamics in La2-xBaxCuO4 superconductor based on DFT method
A
Tavana
author
C
Ambrosch-draxl
author
M
Akhavan
author
text
article
2019
per
Electron-phonon coupling parameters are calculated for La2-x BaxCuO4 cuprate superconductor in a wide range of dopings, from undoped to overdoped compounds. In this study we aim to study the quality of such calculations based on DFT method so, the results of σ GGA+U electronic structure calculations are also investigated. The obtained value for electron-phonon coupling is in the same order of previous calculations but, the value obtained for the Hubbard U parameter shows that, such methods are poor in the estimation of electronic correlations to decide about the role of phonons in these compounds based on their results. Moreover, existence of several structural phase transitions with temperature and doping, lead to larger error in these calculations. Based on the calculated phonon dispersions, structural phase transitions can be resulted which shows the ability of DFT in the study of structural properties and the weakness of the strongly correlations in this properties.
Iranian Journal of Physics Research
https://www.psi.ir/physics_society_iran_1_home
1682-6957
10
v.
2
no.
2019
165
168
http://ijpr.iut.ac.ir/article_874_5a7e7caf2d537237ecb0582eb2ba5c4a.pdf