Two-Component Behavior of Cuprate Superconductors from NMR Shifts

2011 ◽  
Vol 700 ◽  
pp. 1-6
Author(s):  
Damian Rybicki ◽  
Martin Greven ◽  
Juergen Haase ◽  
Thomas Meissner ◽  
Swee K. Goh ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Cuprate Superconductors ◽  
Ambient Pressure ◽  
Superconducting Transition ◽  
Electronic Components ◽  
Temperature Dependent ◽  
Nmr Data ◽  
Two Component ◽  
Shift Data

NMR spin shift data of La1:85Sr0:15CuO4, HgBa2CuO4+ at ambient pressure, andof YBa2Cu4O8 at pressure up to 63 kbar are discussed that fail the traditional single-electronicuid picture used for the discussion of NMR data. Instead the results point to a commonexplanation for all three systems in terms of two electronic components. One of them hasa temperature-dependent magnetic susceptibility while the second component, as well as itscoupling to the rst component, are constant above the superconducting transition temperatureTc. All susceptibilities vanish below Tc.

IMPACT OF NANO-Mo ADDITION/SUBSTITUTION ON THE PHASE FORMATION AND SUPERCONDUCTIVITY OF Mg1-xMoxB2 (x=0.0to 0.50)

2007 ◽  
Vol 21 (14) ◽  
pp. 875-883 ◽  
Author(s):  
MONIKA MUDGEL ◽  
V. P. S. AWANA ◽  
H. KISHAN ◽  
RAJEEV RAWAT ◽  
A. V. NARLIKAR ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Ambient Pressure ◽  
Upper Critical Field ◽  
Zero Field ◽  
Superconducting Transition ◽  
Irreversibility Field ◽  
Sharp Transition ◽  
Mo Content ◽  
Applied Fields

Bulk polycrystalline samples of nano- Mo doped MgB 2 were synthesized by Fe tube encapsulation at ambient pressure under argon annealing (850°C). Mo substitution takes place successfully at the Mg site in Mg 1-x Mo x B 2 only till x=0.2. For higher (x>0.2) Mo content the same did not enter the MgB 2 lattice but rather forms an isomorphic lattice in the host with decreased c but an increased a-parameter. The ρ(T) measurements showed superconducting transition temperature (T c ) of around 36 K for all the samples till x=0.3 and slightly decreased values of 35 and 34 K for x=0.4 and 0.5 samples, respectively. Resistivity under magnetic field [R(T)H] experiments showed distinct single peaks in dρ/dT for all applied fields up to 8 Tesla. The estimated upper critical field H c2 is 8 Tesla for pristine and x=0.2 samples at 15.6 and 19 K, respectively. Thus H c2 increases up to x=0.20 samples and decreases afterwards. Magnetic susceptibility measurements exhibited sharp transition to superconducting state with a sizeable diamagnetic signal at 38 K (T c ) in zero field-cooled measurements. Commendable current density (J c ) of up to 105 A/cm2 in 1–2 T (Tesla) fields at temperatures (T) of up to 10 K is seen from magnetization measurements invoking the Bean's critical state model for pristine samples. For higher fields above 2.5 Tesla the J c (H) characteristics of x=0.1 and 0.2 samples were found to be slightly superior to that for pristine samples with enhanced H irr (irreversibility field).

scholarly journals Unconventional 17O and 63Cu NMR shift components in cuprate superconductors

2020 ◽  
Vol 34 (19n20) ◽  
pp. 2040047 ◽  
Author(s):  
D. Pavićević ◽  
M. Avramovska ◽  
J. Haase
Keyword(s):  
Cuprate Superconductors ◽  
Spin Fluctuations ◽  
Spin Component ◽  
Temperature Dependent ◽  
Relaxation Data ◽  
As Doping ◽  
Electronic Spin ◽  
Single Temperature ◽  
Two Component ◽  
Properties Of Materials

Nuclear magnetic resonance (NMR) is a fundamental bulk probe that provides key information about the electronic properties of materials. Very recently, the analysis of all available planar copper shift as well as relaxation data proved that while the shifts cannot be understood in terms of a single temperature-dependent spin component, relaxation can be explained with one dominating Fermi liquid-like component, without enhanced electronic spin fluctuations. For the shifts, a doping-dependent isotropic term as well as doping-independent anisotropic term became obvious. Here, we focus on planar [Formula: see text]O NMR shifts and quadrupole splittings. Surprisingly, we find that they demand, independently, a similar two-component scenario and confirm most of the previous conclusions concerning the properties of the spin components, in particular that a negative spin polarization survives in the superconducting state. This should have consequences for the pairing scenario.

Antiferromagnetic behavior in Y–Ba–(Cu1−xScx)–O

1989 ◽  
Vol 4 (3) ◽  
pp. 467-469 ◽  
Author(s):  
A. Chakraborty ◽  
X. D. Chen ◽  
F. Zuo ◽  
B. R. Patton ◽  
J. R. Gaines ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Composition Range ◽  
Second Phase ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Susceptibility Study ◽  
New Phase ◽  
Antiferromagnetic Behavior

We report the results on x-ray diffraction and magnetic susceptibility study of Y–Ba–(Cu1−xScx)–O. The materials were prepared in a stoichiometry corresponding to Y1Ba2(Cu1−xScx)3O7. Although x-ray analysis reveals the increasing presence of a subtle second phase with increasing Sc content, the superconducting transition temperature and resistivity did not change substantially in the composition range 0.0  x ≤ 0.15. In contrast, the magnetic susceptibility studies showed dramatic changes. Although Sc3+ has no spin by itself, an enhanced paramagnetic Curie susceptibility was observed above Tc with a moment of 1.5 μB per Sc. At 16 K a sharp cusp is observed in the temperature dependent susceptibility corresponding to the onset of a three-dimensionally ordered antiferromagnetic state. These results are discussed in terms of an additional previously unreported phase of Y–Ba–(Cu–Sc)–O that has an antiferromagnetic Néel temperature of 16 K. For composition of x = 1.0, a new phase is formed which is nonmagnetic.

SIGNATURE OF LOCAL STRUCTURE ANOMALY AT Tc IN THE Nb3Ge SUPERCONDUCTOR

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1713-1719 ◽  
Author(s):  
M. FILLIPPI ◽  
N. L. SAINI ◽  
H. OYANAGI ◽  
A. BIANCONI
Keyword(s):  
Local Structure ◽  
Cuprate Superconductors ◽  
Waller Factor ◽  
Superconducting Transition ◽  
Temperature Dependent ◽  
Local Electron ◽  
Atomic Displacements ◽  
Debye Waller Factor ◽  
The One ◽  
X Ray Absorption

We report local structure of Nb3Ge intermetallic superconductor by Ge K-edge extended X-ray absorption fine structure (EXAFS) measurements performed in the temperature range of 6–300 K, with an emphasis to determine the local and instantaneous atomic displacements across the superconducting transition temperature T c . We find that the temperature dependent correlated Debye–Waller factor of the Ge-Nb bonds shows a drop at the T c while cooling the sample, similar to the one observed in the high-T c cuprate superconductors. The results provide a clear indication of an intimacy between the local atomic displacements and the short coherence superconductivity, and suggests that local electron-lattice interaction should be considered to explain the high-T c superconductivity in these materials.

NORMAL STATE MAGNETISM OF Zn-DOPED AND OXYGEN DEFICIENT CaLaBaCu3O7 SUPERCONDUCTOR

1996 ◽  
Vol 10 (13) ◽  
pp. 619-625 ◽  
Author(s):  
V.P.S. AWANA ◽  
D.A. LANDINEZ ◽  
J.M. FERREIRA ◽  
J. ALBINO AGUIAR ◽  
RAJVIR SINGH ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Transition Temperature ◽  
Magnetic Moment ◽  
Normal State ◽  
Vital Role ◽  
Superconducting Transition ◽  
Temperature Dependent ◽  
Pristine Sample ◽  
Zn Substitution ◽  
Localized Magnetic Moment

Both on-site Zn substitution and oxygen deficiencies in the CaLaBaCu 3 O 7 system decrease the superconducting transition temperature T c of the pristine sample. We observed that the normal state magnetism, measured in a field of 5 KOe, shows a Curie-Weiss behavior, in terms of a localized magnetic moment, presumably on Cu sites, in both cases. The pristine system, i.e. without Zn substitution or oxygen deficiencies, shows a weakly temperature dependent small magnetic susceptibility, in the normal state, i.e. above T c . It has been argued that the normal state magnetism of HTSC systems plays a vital role in determining the T c of these materials.

Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

2013 ◽  
Vol 68 (9) ◽  
pp. 971-978 ◽  
Author(s):  
Inga Schellenberg ◽  
Ute Ch. Rodewald ◽  
Christian Schwickert ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Magnetic Moment ◽  
Induction Furnace ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Arc Melting ◽  
Intermediate Valent

The ternary antimonides RE4T7Sb6 (RE=Gd-Lu; T =Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U4Re7Si6 type, space group Im3m with a=862.9(2) pm, wR2=0.0296, 163 F2 values for Er4Ru7Sb6; a=864.1(1) pm, wR2=0.1423, 153 F2 values for Yb4Ru7Sb6; a=872.0(2) pm, wR2=0.0427, 172 F2 values for Tb4Rh7Sb6; and a=868.0(2) pm, wR2=0.0529, 154 F2 values for Er4Rh7Sb6, with 10 variables per refinement. The structures have T1@Sb6 octahedra and slightly distorted RE@T26Sb6 cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu4Ru7Sb6 is Pauli-paramagnetic. The antimonides RE4Ru7Sb6 with RE=Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy4Ru7Sb6, Ho4Ru7Sb6 and Er4Ru7Sb6, respectively, while Tm4Ru7Sb6 remains paramagnetic. Yb4Ru7Sb6 is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) μB per Yb as compared to 4.54 μB for a free Yb3+ ion

MAGNETIC BEHAVIOUR OF UPdAl, UCuGa AND UCuSn

1993 ◽  
Vol 07 (01n03) ◽  
pp. 850-854 ◽  
Author(s):  
V.H. TRAN ◽  
R. TROĆ
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Type Structure ◽  
Complex Structures ◽  
Temperature Dependent ◽  
Antiferromagnetic Ordering

Magnetic susceptibility and electrical resistivity have been measured on UCuGa, UCu1+xSn1−x, (x=0 and 0.1), and UPdAl. The first two compounds, crystallizing in the hexagonal CaIn2-type structure, show at low temperatures an antiferromagnetic ordering probably with complex structures. UPdAl, which adopts the orthorhombic TiNiSi-type structure, was found to be a weakly temperature-dependent paramagnet down to 4.2 K.

Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

2002 ◽  
Vol 17 (11) ◽  
pp. 2960-2965 ◽  
Author(s):  
E. Arushanov ◽  
L. Ivanenko ◽  
D. Eckert ◽  
G. Behr ◽  
U. K. Rößler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
External Field ◽  
Single Crystals ◽  
Spin Glasses ◽  
Paramagnetic Centers ◽  
Temperature Dependent ◽  
Paramagnetic Curie Temperature ◽  
Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

Variations in magnetic properties of Mexican serpentinites and related micro-textures 

2021 ◽  
Author(s):  
Sandra B. Ramírez-García ◽  
Luis M. Alva-Valdivia
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Anisotropy Of Magnetic Susceptibility ◽  
Ultramafic Rocks ◽  
Magnetic Carrier ◽  
Temperature Dependent ◽  
Geochemical Studies ◽  
The Relationship ◽  
Magnetite Formation

<p>Magnetite formation of serpentinized ultramafic rocks leads to variations in the magnetic properties of serpentinites; however, magnetite precipitation is still on debate.</p><p>In this work, we analyzed 60 cores of ultramafic rocks with a variety of serpentinization degrees. These rocks belong to the ultramafic-mafic San Juan de Otates complex in Guanajuato, Mexico. Geochemical studies have been previously conducted, enabling us to compare changes in the magnetic properties against the chemical variations generated by the serpentinization process. By studying the density and magnetic properties such as anisotropy of magnetic susceptibility, hysteresis curves as well as magnetic and temperature-dependent susceptibility and, we were able to identify the relationship between magnetic content and serpentinization degree, the predominant magnetic carrier, and to what extent the magnetite grain size depends on the serpentinization.  Variations in these parameters allowed us to better constrain the temperature at which serpentinization occurred, the generation of other Fe-rich phases such as Fe-brucite and/or Fe-rich serpentine as well as distinctive rock textures formed at different serpentinization degrees.</p>

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