1,134 research outputs found
RKKY interaction in three-dimensional electron gases with linear spin-orbit coupling
We theoretically study the impacts of linear spin-orbit coupling (SOC) on the
Ruderman-Kittel-Kasuya-Yosida interaction between magnetic impurities in two
kinds of three-dimensional noncentrosymmetric systems. It has been found that
linear SOCs lead to the Dzyaloshinskii-Moriya interaction and the Ising
interaction, in addition to the conventional Heisenberg interaction. These
interactions possess distinct range functions from three dimensional electron
gases and Dirac/Weyl semimetals. In the weak SOC limit, the Heisenberg
interaction dominates over the other two interactions in a moderately large
region of parameters. Sufficiently strong Rashba SOC makes the
Dzyaloshinskii-Moriya interaction or the Ising interaction dominate over the
Heisenberg interaction in some regions. The change in topology of the Fermi
surface leads to some quantitative changes in periods of oscillations of range
functions. The anisotropy of Ruderman-Kittel-Kasuya-Yosida interaction in
bismuth tellurohalides family BiTe ( = Br, Cl, and I) originates from
both the specific form of Rashba SOC and the anisotropic effective mass. Our
work provides some insights into understanding observed spin textures and the
application of these materials in spintronics.Comment: 11 pages, 4 figures, Final Version in PR
Internal Curing by SAP in Ultra-High Strength Concrete with Cement-Silica Fume-Fly Ash Binder
Super-absorbed polymer (SAP) is an effective internal curing materials for reducing autogenous shrinkage and improving cracking resistance of ultra-high-strength concrete (UHSC). This study investigated the compressive strength, shrinkage properties of UHSC with cement–silica fume–fly ash binder. The composition of the binder was designed using seven-batch factorial design method. The relationships between the binder composition and the properties were expressed in contours. Results showed that, silica fume could improve the compressive strength and total shrinkage of UHSC. However fly ash reduced the compressive strength and total shrinkage of UHSC to certain extent. On the other hand, under the internal curing of SAP, the silica fume and fly ash demonstrated positive synergistic effects on the compressive strength. At the early age of hydration, the effectiveness of internal curing first increases and then decreases with the increase of fly ash and silica fume content. However, at the later age of hydration, the effectiveness of internal curing by SAP reduced because of the pozzolanic activity of silica fume and fly ash
Berry Curvature and Phonon Hall Effect
We establish the general phonon dynamics of magnetic solids by incorporating
the Mead-Truhlar correction in the Born-Oppenheimer approximation. The
effective magnetic-field acting on the phonons naturally emerges, giving rise
to the phonon Hall effect. A general formula of the intrinsic phonon Hall
conductivity is obtained by using the corrected Kubo formula with the energy
magnetization contribution incorporated properly. The resulting phonon Hall
conductivity is fully determined by the phonon Berry curvature and the
dispersions. Based on the formula, the topological phonon system could be
rigorously defined. In the low temperature regime, we predict that the phonon
Hall conductivity is proportional to for the ordinary phonon systems,
while that for the topological phonon systems has the linear dependence
with the quantized temperature coefficient.Comment: 11 pages, derivations added, published versio
NMR relaxation studies of electronic structure in NbSe3
NMR spin-lattice relaxation measurements of the Nb93 resonance for each Nb site were performed on an aligned, multicrystalline NbSe3 sample at different temperatures. Results are associated with local electron densities of states for each of the three crystallographic sites, demonstrating Fermi-surface changes associated with the two charge-density-wave phase transitions. The most significant Fermi-surface changes occur for the yellow and orange crystallographic sites, at the high- and low-temperature phase transitions, respectively. The third site, however, is found to be noninsulating. A comparison is made to band theory and other experimental results
The cortisol awakening response predicts response inhibition in the afternoon of the same day
The cortisol awakening response (CAR) is the rapid increase of cortisol levels 30–45 minutes after awakening in the morning. Numerous studies have indicated the relationship between the CAR and cognition. However, little is known about daily variation in the CAR and cognitive function in healthy adults. The aim of the present study was to investigate whether the CAR predicted the response inhibition function on the same day in both behaviour and the dynamic time course of brain processing. The saliva samples of 47 healthy men were collected at three time points: immediately on awakening, 30 minutes and 45 minutes post-awakening in the morning. Participants performed a Go/NoGo task while electroencephalograms (EEG) were recorded in the afternoon of the same day. The results showed that a greater CAR was associated with a stronger N2. In the sub-group of CAR responders (n = 33) the CAR was negatively related to the false alarm rate of NoGo-trials. Our findings suggested that the CAR was predictive of the function of response inhibition in both the earlier cognitive step (i.e., conflict monitoring) and the behavioural performance of response inhibition on the same day in healthy men
Maximum principle for optimal control of fully coupled forward-backward stochastic differential delayed equations
This paper deals with the optimal control problem in which the controlled system is described by a fully coupled anticipated forward-backward stochastic differential delayed equation. The maximum principle for this problem is obtained under the assumption that the diffusion coefficient does not contain the control variables and the control domain is not necessarily convex. Both the necessary and sufficient conditions of optimality are proved. As illustrating examples, two kinds of linear quadratic control problems are discussed and both optimal controls are derived explicitly.Department of Applied Mathematic
- …