Spin dynamics in theNd2−xCexCuO4system: Estimation of the rate of spin fluctuations

1996 ◽  
Vol 54 (22) ◽  
pp. 16254-16258 ◽  
Author(s):  
Vladimir Chechersky ◽  
Nikolai S. Kopelev ◽  
Amar Nath ◽  
J.-L. Peng ◽  
Richard L. Greene ◽  
...  
Keyword(s):  
Spin Dynamics ◽  
Spin Fluctuations

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 Emergent spin-liquid-like state in the bond-disordered breathing pyrochlore

2020 ◽  
Author(s):  
Suheon Lee ◽  
Seunghwan Do ◽  
W.-J. Lee ◽  
Y.-S. Choi ◽  
Johan Van Tol ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Spin Dynamics ◽  
Muon Spin ◽  
Quantum Spin ◽  
Spin Fluctuations ◽  
Spin Liquid ◽  
Spin Liquids ◽  
Magnetic Ground State ◽  
Magnetic Specific Heat ◽  
State Of Matter

Abstract A breathing pyrochlore system is predicted to host a variety of quantum spin liquids. However, perturbations beyond nearest-neighbor Heisenberg interaction are an obstacle to identifying such exotic states. Here, we utilize a bond-alternating disorder to tune a magnetic ground state in the Cr-based breathing pyrochlore. By combining thermodynamic and magnetic resonance techniques, we provide experimental signatures of a spin-liquid-like state in LiGa1-xInxCr4O8 (x=0.2), namely, a nearly T2-dependent magnetic specific heat and a persistent spin dynamics by muon spin relaxation (μSR). Moreover, 7Li NMR, ZF-μSR, and ESR unveil the dichotomic nature of both temporal and thermal spin fluctuations: slowly fluctuating tetramer singlets at high temperatures and a fast fluctuating spin-liquid-like state at low temperatures. Our results suggest that a bond disorder in the breathing pyrochlore offers a new route to achieve an unexplored state of matter.

scholarly journals EFFECT OF NUCLEAR SPINS ON THE ELECTRON SPIN DYNAMICS IN NEGATIVELY CHARGED InP QUANTUM DOTS

2007 ◽  
Vol 06 (03n04) ◽  
pp. 275-278
Author(s):  
I. V. IGNATIEV ◽  
I. YA. GERLOVIN ◽  
S. YU. VERBIN ◽  
W. MARUYAMA ◽  
B. PAL ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Spin ◽  
Spin Dynamics ◽  
Spin Fluctuations ◽  
Nuclear Spins ◽  
Spin Orientation ◽  
Dynamical Nuclear Polarization ◽  
Electron Spin Dynamics ◽  
Kinetics Of ◽  
Inp Quantum Dots

Kinetics of polarized photoluminescence of the negatively charged InP quantum dots in weak magnetic field is studied experimentally. Effect of both the nuclear spin fluctuations and the dynamical nuclear polarization on the electron spin orientation is observed.

INTERMEDIATE VALENCE METALS

2008 ◽  
Vol 22 (13) ◽  
pp. 1273-1295 ◽  
Author(s):  
JON LAWRENCE
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Ground State ◽  
Fermi Liquid ◽  
Spin Dynamics ◽  
The Other ◽  
Spin Fluctuations ◽  
Intermediate Valence ◽  
Neutron Spectra ◽  
Kondo Impurities

The ground state of rare earth intermediate valence (IV) metals is that of a heavy mass Fermi liquid. The transport, optical conductivity, dHvA signals, and Q-resolved neutron spectra reflect the existence of a Fermi surface with strongly renormalized masses and a hybridization gap. On the other hand, properties such as the susceptibility, specific heat, valence and spin dynamics that are dominated by the spin fluctuations, which are highly localized, can be understood qualitatively (and sometimes quantitatively) as those of a collection of non-interacting Anderson/Kondo impurities. Anomalies exist in some compounds both in the low temperature behavior and in the rate of crossover from Fermi liquid to local moment behavior which may reflect non-universal behavior of the Anderson lattice.

Fluctuations of Electron and Nuclear Spins

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Thermal Equilibrium ◽  
Spin Dynamics ◽  
Spin Systems ◽  
Spin Fluctuations ◽  
Quantum Mechanical ◽  
Nuclear Spins ◽  
Spin Noise ◽  
Stochastic Fluctuations ◽  
Noise Spectroscopy ◽  
Mechanical Nature

In thermal equilibrium, both electron and nuclear spin systems are unpolarized on average, but characterized by nonzero fluctuations. These fluctuations are inevitable due to the quantum-mechanical nature of spin. The physics of spin fluctuations in electron and nucelar systems is studied in this chapter. The intensity and dynamics of these inevitable stochastic fluctuations of spins contain information on spin relaxation and decoherence times, spin precession period, and interactions in spin systems. The theory of spin fluctuations in semiconductor nanosystems as well as experimental advances in the field of spin noise spectroscopy are reviewed. Specific situations where the spin noise spectroscopy can be particularly useful for spin dynamics studies are discussed, the analysis of recent progress in the field of nonequlibrium spin fluctuations is also presented.

scholarly journals Controllable freezing of the nuclear spin bath in a single-atom spin qubit

2020 ◽  
Vol 6 (27) ◽  
pp. eaba3442 ◽  
Author(s):  
Mateusz T. Mądzik ◽  
Thaddeus D. Ladd ◽  
Fay E. Hudson ◽  
Kohei M. Itoh ◽  
Alexander M. Jakob ◽  
...  
Keyword(s):  
Electron Spin ◽  
Nuclear Spin ◽  
Quantum Coherence ◽  
Spin Dynamics ◽  
Spin Fluctuations ◽  
Single Atom ◽  
Spin Qubits ◽  
Nuclear Dynamics ◽  
Spin Bath ◽  
Spin Qubit

The quantum coherence and gate fidelity of electron spin qubits in semiconductors are often limited by nuclear spin fluctuations. Enrichment of spin-zero isotopes in silicon markedly improves the dephasing time T2*, which, unexpectedly, can extend two orders of magnitude beyond theoretical expectations. Using a single-atom 31P qubit in enriched 28Si, we show that the abnormally long T2* is due to the freezing of the dynamics of the residual 29Si nuclei, caused by the electron-nuclear hyperfine interaction. Inserting a waiting period when the electron is controllably removed unfreezes the nuclear dynamics and restores the ergodic T2* value. Our conclusions are supported by a nearly parameter-free modeling of the 29Si nuclear spin dynamics, which reveals the degree of backaction provided by the electron spin. This study clarifies the limits of ergodic assumptions in nuclear bath dynamics and provides previously unidentified strategies for maximizing coherence and gate fidelity of spin qubits in semiconductors.

Measuring random spin fluctuations for perturbation-free probes of spin dynamics and magnetic resonance (Invited Paper)

2005 ◽  
Author(s):  
Scott A. Crooker ◽  
Dwight G. Rickel ◽  
Alexander V. Balatsky ◽  
Darryl L. Smith
Keyword(s):  
Magnetic Resonance ◽  
Spin Dynamics ◽  
Spin Fluctuations

scholarly journals Suppression of nuclear spin fluctuations in an InGaAs quantum dot ensemble by GHz-pulsed optical excitation

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
E. Evers ◽  
N. E. Kopteva ◽  
I. A. Yugova ◽  
D. R. Yakovlev ◽  
D. Reuter ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Optical Excitation ◽  
Transverse Magnetic ◽  
Repetition Frequency ◽  
Spin Fluctuations ◽  
Optical Transitions ◽  
Singly Charged ◽  
Electron Spin Dynamics

AbstractThe coherent electron spin dynamics of an ensemble of singly charged (In,Ga)As/GaAs quantum dots in a transverse magnetic field is driven by periodic optical excitation at 1 GHz repetition frequency. Despite the strong inhomogeneity of the electron g factor, the spectral spread of optical transitions, and the broad distribution of nuclear spin fluctuations, we are able to push the whole ensemble of excited spins into a single Larmor precession mode that is commensurate with the laser repetition frequency. Furthermore, we demonstrate that an optical detuning of the pump pulses from the probed optical transitions induces a directed dynamic nuclear polarization and leads to a discretization of the total magnetic field acting on the electron ensemble. Finally, we show that the highly periodic optical excitation can be used as universal tool for strongly reducing the nuclear spin fluctuations and preparation of a robust nuclear environment for subsequent manipulation of the electron spins, also at varying operation frequencies.

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