Neutron scattering of H.T.S.C. Materials : Zn substituted Versus Pure YBCO, Nuclear and Magnetic Structures, Spin Excitations.

1994 ◽  
Vol 376 ◽  
Author(s):  
G. Collin ◽  
R. Villeneuve ◽  
Y. Sidis ◽  
Ph. Bourges ◽  
B. Hennion ◽  
...  
Keyword(s):  
Magnetic Impurity ◽  
Spin Dynamics ◽  
Magnetic Behavior ◽  
Dilution Effect ◽  
Magnetic Scattering ◽  
Magnetic Structures ◽  
Zn Substitution ◽  
Spin Excitations ◽  
Temperature Dependance ◽  
Pure Ybco

ABSTRACTThe Zn substitution on Cu(2) sites in YBa2(Cu1-yZny)3O6+x materials is most probably limited to yzn ≈ 0.04. Results of neutron diffraction associated with NMR and μ+SR results reveal ; i) a lowering of TN in the pure AF region x≤0.20 due to a dilution effect of the antiferromagnetic lattice by a static non magnetic impurity, ii) the existence of a non conventionnal magnetic behavior within the intermediate region x≥0.35 characterized by an unusual temperature dependance of magnetic intensities, a reentrancy and the existence of diffuse magnetic scattering (this region is much broader in oxygen composition for Zn-doped than for pure YBCO),iii) an unusual spin dynamics in the "doped A-F phase" which corresponds to a coupling of magnetic excitations to the hole dynamics.

Neutron Studies of the Iron-based Family of High Tc Magnetic Superconductors

2008 ◽  
Vol 1148 ◽  
Author(s):  
Jeffrey W. Lynn
Keyword(s):  
Magnetic Order ◽  
Spin Dynamics ◽  
Magnetic Scattering ◽  
Anisotropic Pressure ◽  
Itinerant Electron ◽  
Superconducting Transition ◽  
Orthogonal Direction ◽  
Magnetic Structures ◽  
Se Doping ◽  
Iron Based

AbstractWe briefly review recent neutron scattering investigations carried out at the NIST Center for Neutron Research on the crystal structures, magnetic structures, and spin dynamics of the iron-based ROFe(As,P) (R=La, Ce, Pr, Nd), and (Ba,Sr,Ca)Fe2As2 systems. All the undoped materials exhibit universal behavior, where a tetragonal-to-orthorhombic structural transition occurs between ˜100−220 K, below which the systems become antiferromagnets. The magnetic structure within the a-b plane consists of chains of parallel Fe spins that are coupled antiferromagnetically in the orthogonal direction, with an ordered moment typically less than one Bohr magneton. Hence these are itinerant electron magnets, with a spin structure that is consistent with Fermi-surface nesting and a spin wave bandwidth ˜200 meV. The rare-earth moments order antiferromagnetically at low T like ‘conventional’ magnetic-superconductors. With doping, the structural and magnetic transitions are suppressed in favor of superconductivity, with superconducting transition temperatures up to 56 K, while the Ce crystal field linewidths are affected when superconductivity sets in. The application of pressure in CaFe2As2 transforms the system from a magnetically ordered orthorhombic material to a ‘collapsed’ non-magnetic tetragonal system which is superconducting at lower T when anisotropic pressure is applied. Fe1+xTe shows a transition from a monoclinic to orthorhombic low T structure with increasing x, and a crossover from commensurate to incommensurate magnetic order. Se doping suppresses the magnetic order, while incommensurate magnetic scattering is observed in the superconducting regime.

Skyrmions

2017 ◽  
Author(s):  
Olle Eriksson ◽  
Anders Bergman ◽  
Lars Bergqvist ◽  
Johan Hellsvik
Keyword(s):  
Spin Dynamics ◽  
Important Application ◽  
Point Of View ◽  
Theoretical Point ◽  
Magnetic Texture ◽  
Magnetic Structures ◽  
Spin Excitations ◽  
Magnetic Skyrmions ◽  
External Stimuli

An important application of spin dynamics is the response of a magnetic material subjected to an external stimuli. In the previous chapter we discussed the response of primarily ferromagnets to temperature fluctuations that manifest itself to spin excitations and magnons. In this chapter, we are concerned about magnetic materials with more complicated magnetic texture, such as spin spirals and topological magnetic structures, in particular magnetic skyrmions. Magnetic skyrmions has many appealing and intriguing features that make them interesting both for possible applications but also from a pure theoretical point of view.

scholarly journals Evolution of spin excitations from bulk to monolayer FeSe

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonathan Pelliciari ◽  
Seher Karakuzu ◽  
Qi Song ◽  
Riccardo Arpaia ◽  
Abhishek Nag ◽  
...  
Keyword(s):  
Quantum Monte Carlo ◽  
Spin Dynamics ◽  
Spin Fluctuations ◽  
Superconducting Transition ◽  
Pairing Mechanism ◽  
Range Magnetic Order ◽  
X Ray Scattering ◽  
Spin Excitations ◽  
Order Of Magnitude ◽  
Long Range Magnetic Order

AbstractIn ultrathin films of FeSe grown on SrTiO3 (FeSe/STO), the superconducting transition temperature Tc is increased by almost an order of magnitude, raising questions on the pairing mechanism. As in other superconductors, antiferromagnetic spin fluctuations have been proposed to mediate SC making it essential to study the evolution of the spin dynamics of FeSe from the bulk to the ultrathin limit. Here, we investigate the spin excitations in bulk and monolayer FeSe/STO using resonant inelastic x-ray scattering (RIXS) and quantum Monte Carlo (QMC) calculations. Despite the absence of long-range magnetic order, bulk FeSe displays dispersive magnetic excitations reminiscent of other Fe-pnictides. Conversely, the spin excitations in FeSe/STO are gapped, dispersionless, and significantly hardened relative to its bulk counterpart. By comparing our RIXS results with simulations of a bilayer Hubbard model, we connect the evolution of the spin excitations to the Fermiology of the two systems revealing a remarkable reconfiguration of spin excitations in FeSe/STO, essential to understand the role of spin fluctuations in the pairing mechanism.

scholarly journals Probing nanoscale behavior of magnetic materials with soft X-ray spectromicroscopy

2012 ◽  
Vol 1 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Peter Fischer ◽  
Charles S. Fadley
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Spin Dynamics ◽  
Magnetic Nanostructures ◽  
Magnetic Behavior ◽  
Research Area ◽  
X Ray ◽  
Spatially Resolved ◽  
Buried Interfaces ◽  
Analytical Tools

AbstractThe magnetic properties of matter continue to be a vibrant research area driven both by scientific curiosity to unravel the basic physical processes which govern magnetism and the vast and diverse utilization of magnetic materials in current and future devices, e.g., in information and sensor technologies. Relevant length and time scales approach fundamental limits of magnetism and with state-of-the-art synthesis approaches we are able to create and tailor unprecedented properties. Novel analytical tools are required to match these advances and soft X-ray probes are among the most promising ones. Strong and element-specific magnetic X-ray dichroism effects as well as the nanometer wavelength of photons and the availability of fsec short and intense X-ray pulses at upcoming X-ray sources enable unique experimental opportunities for the study of magnetic behavior. This article provides an overview of recent achievements and future perspectives in magnetic soft X-ray spectromicroscopies which permit us to gain spatially resolved insight into the ultrafast spin dynamics and the magnetic properties of buried interfaces of advanced magnetic nanostructures.

The Effect of Partial Substitution of Non-Magnetic Impurity Zn on the Magnetic Moments of Eu1.88Ce0.12Cu1-yZnyO4+α-δ

2021 ◽  
Vol 1028 ◽  
pp. 15-20
Author(s):  
Muhammad Abdan Syakuur ◽  
Yati Maryati ◽  
Togar Saragi ◽  
Risdiana
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Magnetic Impurity ◽  
Magnetic Moments ◽  
Magnetic Behavior ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
Magnetic Susceptibility Data ◽  
Susceptibility Data ◽  
Volume Unit

Structure and magnetic properties of electron-doped superconducting cuprates have been investigated in order to study the effect of magnetic impurity to its physical properties. Here, we reported structure and magnetic properties of Eu1.88Ce0.12Cu1-yZnyO4+α-δ (ECCZO) with y = 0 and 0.03. The properties of ECCZO have been studied from X-ray diffraction data and temperature dependence of magnetic susceptibility data, to elucidate the effect of partial substitution of non-magnetic impurity Zn for Cu to its structure, Tc and the value of magnetic moments per unit volume extracted from susceptibility data in normal state. Magnetic-susceptibility measurements were carried out down to 2 K on-field cooling at 5 Oe for Eu1.88Ce0.12Cu1-yZnyO4+a-d with y = 0 and 0.03. For ECCZO sample with y = 0 and d = 0.0669 indicated the change of magnetic behavior from paramagnetic to diamagnetic below 12 K which is addressed to the Tc onset of this samples. Diamagnetic behavior is observed starting from about 12 K. Above 12 K, all samples show paramagnetic behavior with the values of the magnetic moment in every volume unit increased with increasing Zn.

scholarly journals Ultrafast optically induced spin transfer in ferromagnetic alloys

2020 ◽  
Vol 6 (3) ◽  
pp. eaay8717 ◽  
Author(s):  
M. Hofherr ◽  
S. Häuser ◽  
J. K. Dewhurst ◽  
P. Tengdin ◽  
S. Sakshath ◽  
...  
Keyword(s):  
Density Functional ◽  
Spin Dynamics ◽  
Research Area ◽  
Spin Transfer ◽  
Optical Manipulation ◽  
Functional Theory ◽  
Control Schemes ◽  
All Optical ◽  
Spin Excitations ◽  
Experimental Findings

The vision of using light to manipulate electronic and spin excitations in materials on their fundamental time and length scales requires new approaches in experiment and theory to observe and understand these excitations. The ultimate speed limit for all-optical manipulation requires control schemes for which the electronic or magnetic subsystems of the materials are coherently manipulated on the time scale of the laser excitation pulse. In our work, we provide experimental evidence of such a direct, ultrafast, and coherent spin transfer between two magnetic subsystems of an alloy of Fe and Ni. Our experimental findings are fully supported by time-dependent density functional theory simulations and, hence, suggest the possibility of coherently controlling spin dynamics on subfemtosecond time scales, i.e., the birth of the research area of attomagnetism.

scholarly journals Molecular Field Calculation of Magnetization on Single Crystal

2008 ◽  
Vol 2008 ◽  
pp. 1-4
Author(s):  
A. Himori ◽  
K. Hattori ◽  
T. Shigeoka
Keyword(s):  
Single Crystal ◽  
Field Model ◽  
Magnetic Phase Diagram ◽  
Magnetic Behavior ◽  
Molecular Field ◽  
Ferromagnetic Phase ◽  
Field Calculation ◽  
Magnetic Structures ◽  
Magnetization Processes ◽  
Crystal Compound

Calculation of magnetization of the ternary single crystal compound has been carried out by using the wave-like molecular field model to explain the complex magnetic behavior. The field-induced magnetic structures having the propagation vectors, , , , and (= the field-induced ferromagnetic phase) were proposed. Calculation on the basis of these structures and the antiferromagnetic phase with well reproduces the experimental magnetization processes and - magnetic phase diagram.

The impact of the magnetic impurity phases on the magnetic behavior in valence fluctuating compound Ce 2 Rh 3 Ge

2017 ◽  
Vol 85 ◽  
pp. 144-148 ◽  
Author(s):  
Paweł Skornia ◽  
Jerzy Goraus ◽  
Janusz Koperski ◽  
Marcin Wojtyniak ◽  
Andrzej Ślebarski
Keyword(s):  
Magnetic Impurity ◽  
Magnetic Behavior ◽  
Impurity Phases ◽  
The Impact
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