scholarly journals 57Fe and 151Eu Mössbauer studies of 3d-4f spin interplay in EuFe2−xNixAs2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
K. Komędera ◽  
J. Gatlik ◽  
A. Błachowski ◽  
J. Żukrowski ◽  
D. Rybicki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Order ◽  
Parent Compound ◽  
Density Wave ◽  
Hyperfine Magnetic Field ◽  
Spin Density Wave ◽  
Spin Reorientation ◽  
Substitution Level ◽  
Ni Substitution ◽  
The Eu

AbstractThe EuFe2−xNixAs2 (with 0 ≤ x ≤ 0.4) compounds exhibiting 3d and/or 4f magnetic order were investigated by means of 57Fe and 151Eu Mössbauer spectroscopy. Additionally, results for EuNi2As2 are reported for comparison. It was found that spin-density-wave order of the Fe itinerant moments is monotonically suppressed by Ni-substitution. However, the 3d magnetic order survives at the lowest temperature up to at least x = 0.12 and it is certainly completely suppressed for x = 0.20. The Eu localized moments order regardless of the Ni concentration, but undergo a spin reorientation with increasing x from alignment parallel to the a-axis in the parent compound, toward c-axis alignment for x > 0.07. Change of the 4f spins ordering from antiferromagnetic to ferromagnetic takes place simultaneously with a disappearance of the 3d spins order what is the evidence of a strong coupling between magnetism of Eu2+ ions and the conduction electrons of [Fe2−xNixAs2]2- layers. The Fe nuclei experience the transferred hyperfine magnetic field due to the Eu2+ ordering for Ni-substituted samples with x > 0.04, while the transferred field is undetectable in EuFe2As2 and for compound with a low Ni-substitution level. It seems that the 4f ferromagnetic component arising from a tilt of the Eu2+ moments to the crystallographic c-axis leads to the transferred magnetic field at the Fe atoms. Superconductivity is not observed down to 1.8 K, although a comparison with 57Fe and 151Eu Mössbauer data for EuFe2As2-based superconductors indicates a similar magnetic structure.

scholarly journals 57Fe and 151Eu Mössbauer Studies of 3d-4f Spin Interplay in EuFe2-xNixAs2

2021 ◽  
Author(s):  
K. Komędera ◽  
J. Gatlik ◽  
A. Błachowski ◽  
J. Żukrowski ◽  
D. Rybicki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Order ◽  
Parent Compound ◽  
Density Wave ◽  
Hyperfine Magnetic Field ◽  
Spin Density Wave ◽  
Spin Reorientation ◽  
Substitution Level ◽  
Ni Substitution ◽  
The Eu

Abstract The EuFe2-xNixAs2 compounds exhibiting 3d and/or 4f magnetic order were investigated by means of 57Fe and 151Eu Mössbauer spectroscopy. Additionally, results for the end members of this system, i.e. EuFe2As2 and EuNi2As2, are reported for comparison. It was found that spin-density-wave order of the Fe itinerant moments is monotonically suppressed by Ni-substitution. However, the 3d magnetic order survives at the lowest temperature up to at least x = 0.12 and it is certainly completely suppressed for x = 0.20. The Eu localized moments order regardless of the Ni concentration, but undergo a spin reorientation with increasing x from the alignment parallel to the a-axis in the parent compound, toward c-axis alignment for x > 0.07. The change of the 4f spins ordering from antiferromagnetic to ferromagnetic takes place simultaneously with a disappearance of the 3d spins order what is the evidence of a strong coupling between magnetism of Eu2+ ions and the conduction electrons of [Fe2-xNixAs2]2- layers. The Fe nuclei experience the transferred hyperfine magnetic field due to the Eu2+ ordering for Ni-substituted samples with x > 0.04, while the transferred field is undetectable in EuFe2As2 and for compound with a low Ni-substitution level. It seems that the 4f ferromagnetic component arising from a tilt of the Eu2+ moments to the crystallographic c-axis leads to the transferred magnetic field at the Fe atoms. The superconductivity is not observed down to 1.8 K, although a comparison with 57Fe and 151Eu Mössbauer data for EuFe2As2-based superconductors indicates a similar magnetic structure.

Effects of 4d transition metal Pd doping on the magnetic and superconducting properties of 112-type iron pnictide EuFeAs2

2021 ◽  
Author(s):  
Xinhui Zhan ◽  
Xiaolei Yi ◽  
Xiangzhuo Xing ◽  
Meng Li ◽  
Linchao Yu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Electrical Transport ◽  
Parent Phase ◽  
Density Wave ◽  
Spin Density Wave ◽  
Spin Reorientation ◽  
Iron Pnictide ◽  
Pd Doping ◽  
Reentrant Spin Glass ◽  
The Eu

Abstract The recently discovered 112-type EuFeAs2 compound that shows complex Eu-spin magnetism provides a new platform to study the interplay between superconductivity (SC) and magnetism in iron pnictide superconductors. In this paper, by substituting Fe with the 4d transition metal Pd, we have successfully synthesized a series of EuFe1-xPdxAs2 (0 ≤ x ≤ 0.08) samples and studied the doping effect on SC and magnetism by means of electrical transport and magnetization measurements. The systematic evolution of the lattice parameters indicates that the Pd atoms have been successfully substituted into the Fe sites. With Pd doping, the Fe-related spin density wave (SDW) transition at TFe m in the parent phase is rapidly suppressed, and SC simultaneously emerges, exhibiting a domelike shape with a maximum onset transition temperature Tonset c of around 18.5 K at x = 0.04. On the other hand, the Eu-related AFM order at TEu m is suppressed very slowly and persists up to x = 0.08, covering the whole SC dome region. Also, the reentrant spin-glass and spin-reorientation transitions below TEu m remain unchanged with Pd doping. All these results indicate that the Eu spins have little effect on SC in EuFe1-xPdxAs2. Finally, based on the resistivity and magnetization data, the T-x phase diagram of EuFe1-xPdxAs2 is constructed and compared with those of 3d transition metals Co/Ni and La doped ones.

Magnetic-field behavior of the spin-density-wave state in (TMTSF)2AsF6

1995 ◽  
Vol 52 (22) ◽  
pp. 15983-15991 ◽  
Author(s):  
J. L. Musfeldt ◽  
M. Poirier ◽  
P. Batail ◽  
C. Lenoir
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Wave State ◽  
Field Behavior

COLLECTIVE FIELD THEORY TO MAGNETIC-FIELD-INDUCED SPIN-DENSITY-WAVE-STATE IN BECHGAARD SALTS, (TMTSF)2X

1993 ◽  
Vol 07 (19) ◽  
pp. 3415-3421 ◽  
Author(s):  
ALEXANDRE S. ROZHAVSKY
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Chemical Potential ◽  
Density Wave ◽  
Spin Density Wave ◽  
Hall Conductivity ◽  
Chiral Anomaly ◽  
Threshold Field ◽  
Wave State ◽  
Extended States

A field description of spin-density-wave (SDW) in a quasi-two-dimensional metal with open Fermi surface in magnetic field, is proposed. The SDW transition temperature, T c (H), and the Hall conductivity σxy, are calculated. The dependence T c (H) is found to be different from that of the Bardeen-Cooper-Schrieffer model, in particular, a threshold field, H c , found its natural explanation. It is proved that the quantized Hall conductivity arises from the chiral anomaly terms in the effective action provided there is pinning of chemical potential in the gap of extended states.

scholarly journals Mn-induced Fermi-surface reconstruction in the SmFeAsO parent compound

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Meinero ◽  
P. Bonfà ◽  
I. J. Onuorah ◽  
S. Sanna ◽  
R. De Renzi ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Muon Spin ◽  
Magnetic Transition ◽  
Parent Compound ◽  
Density Wave ◽  
Spin Density Wave ◽  
Magnetic Impurities ◽  
Magnetic Fluctuations ◽  
Mn Content ◽  
Electronic Ground

AbstractThe electronic ground state of iron-based materials is unusually sensitive to electronic correlations. Among others, its delicate balance is profoundly affected by the insertion of magnetic impurities in the FeAs layers. Here, we address the effects of Fe-to-Mn substitution in the non-superconducting Sm-1111 pnictide parent compound via a comparative study of SmFe$$_{1-x}$$ 1 - x Mn$$_{x}$$ x AsO samples with $$x(\text{Mn})=$$ x ( Mn ) = 0.05 and 0.10. Magnetization, Hall effect, and muon-spin spectroscopy data provide a coherent picture, indicating a weakening of the commensurate Fe spin-density-wave (SDW) order, as shown by the lowering of the SDW transition temperature $$T_\text{SDW}$$ T SDW with increasing Mn content, and the unexpected appearance of another magnetic order, occurring at $$T^{*} \approx 10$$ T ∗ ≈ 10 and 20 K for $$x=0.05$$ x = 0.05 and 0.10, respectively. We attribute the new magnetic transition at $$T^{*}$$ T ∗ , occurring well inside the SDW phase, to a reorganization of the Fermi surface due to Fe-to-Mn substitutions. These give rise to enhanced magnetic fluctuations along the incommensurate wavevector $$\varvec{Q}_2 =(\pi \pm \delta ,\pi \pm \delta )$$ Q 2 = ( π ± δ , π ± δ ) , further increased by the RKKY interactions among Mn impurities.

High magnetic field NMR investigation of the spin density wave phase of TMTSF2PF6

2002 ◽  
Vol 12 (9) ◽  
pp. 389-389
Author(s):  
W. G. Clark ◽  
F. Zamborsky ◽  
B. Alavi ◽  
P. Vonlanthen ◽  
W. Moulton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Proton Relaxation ◽  
High Magnetic Fields ◽  
Organic Conductor ◽  
First Order ◽  
The Magnetic Field ◽  
Very High

We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF2PF6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than $1O^{-10}$s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.

scholarly journals MAGNETIC FIELD TUNING OF CHARGE AND SPIN ORDER IN THE CUPRATE SUPERCONDUCTORS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3156-3163 ◽  
Author(s):  
A. POLKOVNIKOV ◽  
S. SACHDEV ◽  
M. VOJTA ◽  
E. DEMLER
Keyword(s):  
Magnetic Field ◽  
Ground State ◽  
Charge Density Wave ◽  
Cuprate Superconductors ◽  
Density Wave ◽  
Spin Density Wave ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Spin Order ◽  
New Information

Recent neutron scattering, nuclear magnetic resonance, and scanning tunneling microscopy experiments have yielded valuable new information on the interplay between charge and spin density wave order and superconductivity in the cuprate superconductors, by using a perpendicular magnetic field to tune the ground state properties. We compare the results of these experiments with the predictions of a theory which assumed that the ordinary superconductor was proximate to a quantum transition to a superconductor with co-existing spin/charge density wave order.

Temperature and magnetic field dependences of rapid oscillations in field induced spin-density-wave phase for (TMTSF)2ClO4

1997 ◽  
Vol 86 (1-3) ◽  
pp. 1909-1910 ◽  
Author(s):  
S. Uji ◽  
T. Terashima ◽  
H. Aoki ◽  
J.S. Brooks ◽  
M. Tokumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Wave Phase
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