scholarly journals Spin dynamics of aJ1−J2antiferromagnet and its implications for iron pnictides

2011 ◽  
Vol 84 (15) ◽  
Author(s):  
Pallab Goswami ◽  
Rong Yu ◽  
Qimiao Si ◽  
Elihu Abrahams
Keyword(s):  
Spin Dynamics ◽  
Iron Pnictides

Investigation of Fluctuating Diamagnetism and Spin Dynamics in SmFeAsO1-xFx Superconductors

2010 ◽  
Vol 75 ◽  
pp. 141-146 ◽  
Author(s):  
Giacomo Prando ◽  
Pietro Carretta ◽  
Alessandro Lascialfari ◽  
Attilio Rigamonti ◽  
Samuele Sanna ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Nmr Spectroscopy ◽  
Superconducting Transition Temperature ◽  
Spin Dynamics ◽  
Magnetic Coupling ◽  
Iron Pnictides ◽  
Superconducting Transition ◽  
Squid Magnetometry ◽  
Conduction Electrons ◽  
Underdoped Cuprates

The superconducting iron-pnictides SmFeAsO1-xFx (x = 0.15 and x = 0.2) are studied by means of 19F-NMR spectroscopy and SQUID magnetometry. Fluctuating diamagnetism above Tc is briefly examined, stressing the analogy with the phenomenology in underdoped cuprates. The 19F relaxation rate allows us to infer an indirect magnetic coupling between Sm3+ moments, possibly involving conduction electrons in FeAs bands, with no appreciable effects on crossing the superconducting transition temperature. A comparison between the superconducting samples and the insulating SmOF, often present as spurious phase in SmFeAsO1-xFx pnictides, is also carried out. Relevant differences in the spin dynamics features are found.

scholarly journals Spin dynamics of aJ1-J2-Kmodel for the paramagnetic phase of iron pnictides

2012 ◽  
Vol 86 (8) ◽  
Author(s):  
Rong Yu ◽  
Zhentao Wang ◽  
Pallab Goswami ◽  
Andriy H. Nevidomskyy ◽  
Qimiao Si ◽  
...  
Keyword(s):  
Spin Dynamics ◽  
Paramagnetic Phase ◽  
Iron Pnictides

scholarly journals Impurity effects on spin dynamics in magnetic and superconducting iron pnictides and chalcogenides

2016 ◽  
Vol 254 (1) ◽  
pp. 1600162 ◽  
Author(s):  
M. A. Surmach ◽  
P. Y. Portnichenko ◽  
J. T. Park ◽  
J. A. Rodriguez-Rivera ◽  
D. L. Sun ◽  
...  
Keyword(s):  
Spin Dynamics ◽  
Iron Pnictides ◽  
Impurity Effects ◽  
Pnictides And Chalcogenides

scholarly journals Electron Correlation and Spin Dynamics in Iron Pnictides and Chalcogenides

2013 ◽  
Vol 449 ◽  
pp. 012025 ◽  
Author(s):  
Rong Yu ◽  
Qimiao Si ◽  
Pallab Goswami ◽  
Elihu Abrahams
Keyword(s):  
Electron Correlation ◽  
Spin Dynamics ◽  
Iron Pnictides ◽  
Pnictides And Chalcogenides

The Damping Term, from First Principles

2017 ◽  
Author(s):  
Olle Eriksson ◽  
Anders Bergman ◽  
Lars Bergqvist ◽  
Johan Hellsvik
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Spin Dynamics ◽  
Damping Term ◽  
Functional Theory ◽  
Basic Principles ◽  
Sham Equation ◽  
Damping Parameter ◽  
Simulation Cell

In the previous chapters we described the basic principles of density functional theory, gave examples of how accurate it is to describe static magnetic properties in general, and derived from this basis the master equation for atomistic spin-dynamics; the SLL (or SLLG) equation. However, one term was not described in these chapters, namely the damping parameter. This parameter is a crucial one in the SLL (or SLLG) equation, since it allows for energy and angular momentum to dissipate from the simulation cell. The damping parameter can be evaluated from density functional theory, and the Kohn-Sham equation, and it is possible to determine its value experimentally. This chapter covers in detail the theoretical aspects of how to calculate theoretically the damping parameter. Chapter 8 is focused, among other things, on the experimental detection of the damping, using ferromagnetic resonance.

Strong Coupling of Electron and Nuclear Spins: Outlook and Prospects

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Energy Spectrum ◽  
Charge Carrier ◽  
Strong Coupling ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Spin Polaron ◽  
Nuclear Spins ◽  
Deep Impurity ◽  
Impurity Centers ◽  
Ordered State

In this chapter, some prospects in the field of electron and nuclear spin dynamics are outlined. Particular emphasis is put ona situation where the hyperfine interaction is so strong that it leads to a qualitative rearrangement of the energy spectrum resulting in the coherent excitation transfer between the electron and nucleus. The strong coupling between the spin of the charge carrier and of the nucleus is realized, for example in the case of deep impurity centers in semiconductors or in isotopically purified systems. We also discuss the effect of the nuclear spin polaron, that is ordered state, formation at low enough temperatures of nuclear spins, where the orientation of the carrier spin results in alignment of the spins of nucleus interacting with the electron or hole.

Electron Spin Decoherence by Nuclei

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Electron Spin ◽  
Spin Dynamics ◽  
Magnetic Moments ◽  
Host Lattice ◽  
Spin Model ◽  
Relaxation Processes ◽  
Nuclear Spins ◽  
Model Calculations ◽  
Spin Decoherence ◽  
Quantum Mechanical Approach

The discussion of the electron spin decoherence and relaxation phenomena via the hyperfine interaction with host lattice spins is presented here. The spin relaxation processes processes limit the conservation time of spin states as well as the response time of the spin system to external perturbations. The central spin model, where the spin of charge carrier interacts with the bath of nuclear spins, is formulated. We also present different methods to calculate the spin dynamics within this model. Simple but physically transparent semiclassical treatment where the nuclear spins are considered as largely static classical magnetic moments is followed by more advanced quantum mechanical approach where the feedback of electron spin dynamics on the nuclei is taken into account. The chapter concludes with an overview of experimental data and its comparison with model calculations.

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