共查询到20条相似文献,搜索用时 15 毫秒
1.
The spin-orbit coupled lattice system under Zeeman fields provides an ideal platform to realize exotic pairing states. Notable examples range from the topological superfluid/superconducting (tSC) state, which is gapped in the bulk but metallic at the edge, to the Fulde–Ferrell (FF) state (having a phase-modulated order parameter with a uniform amplitude) and the Larkin–Ovchinnikov (LO) state (having a spatially varying order parameter amplitude). Here, we show that the topological FF state with Chern number (C=−1) (tFF1) and topological LO state with C= 2 (tLO2) can be stabilized in Rashba spin-orbit coupled lattice systems in the presence of both in-plane and out-of-plane Zeeman fields. Besides the inhomogeneous tSC states, in the presence of a weak in-plane Zeeman field, two topological BCS phases may emerge with C=−1 (tBCS1) far from half filling and C= 2 (tBCS2) near half filling. We show intriguing effects such as different spatial profiles of order parameters for FF and LO states, the topological evolution among inhomogeneous tSC states, and different non-trivial Chern numbers for the tFF1 and tLO1,2 states, which are peculiar to the lattice system. Global phase diagrams for various topological phases are presented for both half-filling and doped cases. The edge states as well as local density of states spectra are calculated for tSC states in a 2D strip. 相似文献
2.
C. Brügger F. Kämpfer M. Pepe U.-J. Wiese 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):433-437
The long-range forces between holes in an antiferromagnet are due to
magnon exchange. The one-magnon exchange potential between two holes is
proportional to cos(2 ϕ)/r
2 where r is the distance
vector of the holes and ϕ is the angle between r and an axis of
the square crystal lattice. One-magnon exchange leads to bound states of holes
with antiparallel spins resembling d-wave symmetry. 相似文献
3.
M. V. Chetkin Yu. N. Kurbatova A. I. Akhutkina T. B. Shapaeva 《Journal of Experimental and Theoretical Physics》1999,88(6):1179-1185
Solitary bending waves have been observed on domain boundaries of Néel type in wafers of yttrium orthoferrite, having a very
sharp leading edge and an extended trailing edge and offset as a whole from the domain boundary and moving with high speeds
close to the limiting velocity. Head-on collisions of two such waves of the same amplitude lead to their complete annihilation.
Analogous collisions of two such waves, but of different amplitudes, lead to the appearance of a wave with the difference
amplitude moving in the same direction as the wave of larger amplitude. The solitary bending waves investigated in this study
appear to move under the action of gyroscopic forces acting on magnetic vortices on domain boundaries in yttrium orthoferrite,
analogous to vertical Bloch lines with departure of the magnetization vector from the ac plane. From equality of the gyroscopic force with the friction force acting on the leading edge of the solitary bending wave
we have estimated the amplitudes of these waves and the magnitudes of the topological charges of the magnetic vortices.
Zh. éksp. Teor. Fiz. 115, 2160–2169 (June 1999) 相似文献
4.
Z.-Y. Jiao X.-Y. Kuang X.-F. Huang J.-H. Li M.-L. Duan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(3):297-300
The complete energy matrices
for a d5configuration ion in a tetragonal
ligand-field has been constructed on the basis of the complete set of
basis
of d5configuration (252
dimension), and the relationship between the low-symmetry EPR parameters
b2
0 ,b4
0 and the local distortion parameters has been
established based on the complete energy matrices. As an application, we
have studied the EPR parameters and the local lattice structure of Mn2+
ion doped in tetragonal K2ZnF4 system. The calculation indicated that the local lattice structure around a tetragonal Mn2+ ion center has an expansion distortion. Simultaneously, the local lattice structure parameters R1 =2.0727 ?, R2 =2.0801 ? at room temperature (295 K) and R1
′ = 2.0439 ?, R2
′ =2.05478 ? at low
temperature (4.2 K) are determined. 相似文献
5.
F. Capel C. Moure P. Durán A.R. González-Elipe A. Caballero 《Applied Physics A: Materials Science & Processing》1999,68(1):41-48
2 -doped YTZP ([%mol]3 Y2O3) compositions sintered in the temperature range of 1300 to 1450 °C, the tetragonal zirconia solid solutions field for the
ZrO2-Y2O3-TiO2 system was established. The solubility of TiO2 in YTZP was found to be about 12–[%mol]14 at 1450 °C. Structural characterization of the Ti-YTZP tetragonal zirconia solid
solutions was carried out using X-ray absorption spectroscopy (EXAFS and XANES) to provide information on the environment
of Ti atoms. The electrical behavior in air of the TiO2-doped tetragonal zirconia solid solutions was studied by impedance spectroscopy in the temperature range of 300 to 800 °C,
and it was found that the ionic conductivity decreases with increasing titania content. EXAFS and XANES results show that
as the Ti4+ ions dissolve into the tetragonal zirconia YTZP matrix, a displacement of Ti ions from the center of symmetry takes place,
leading to a non-random substitution of Ti4+ ions on Zr4+ lattice sites. Ti-O bond distances derived from EXAFS indicate that the Ti ion can be in a square-pyramidal arrangement,
i.e., fivefold oxygen-coordinated. As a consequence two kinds of cation–oxygen vacancy associations are created; the high-mobility
oxygen-vacancy–eightfold-coordinated cation (Zr4+) and the low-mobility oxygen-vacancy–fivefold-coordinated cation (Ti4+). This results in a decrease in the global concentration of moving oxygen vacancies and, therefore, in a decrease of the
electrical conductivity.
Received: 1 April 1998/Accepted: 28 September 1998 相似文献
6.
《Surface science》1996,364(2):L555-L562
Pattern formation in the NO + H2 reaction on Rh(111) has been investigated in the 10−6 mbar range using photoelectron emission microscopy (PEEM) as a spatially resolving method. Target patterns, spiral waves and irregular patterns are observed in a T-window of ∼20 K width at around 460 K, located in the transition range between the reactive and unreactive states of the surface. A new species characterized by a work function below that of the clean surface forms upon collision of two wave fronts. This new species is tentatively assigned to subsurface oxygen. The colliding wave fronts start to interact when they are still more than 100 μm apart, thus demonstrating the presence of a long-range diffusional coupling. 相似文献
7.
C. Pinzari Y. Watatani--RID=""--> K. Yonetani 《Communications in Mathematical Physics》2000,213(2):331-379
To any periodic and full C
*-dynamical system , an invertible operator s acting on the Banach space of trace functionals of the fixed point algebra is canonically associated. KMS states correspond
to positive eigenvectors of s. A Perron–Frobenius type theorem asserts the existence of KMS states at inverse temperatures equals the logarithms of the
inner and outer spectral radii of s (extremal KMS states). Examples arising from subshifts in symbolic dynamics, self-similar sets in fractal geometry and noncommutative
metric spaces are discussed.
Certain subshifts are naturally associated to the system, and criteria for the equality of their topological entropy and inverse
temperatures of extremal KMS states are given.
Unital completely positive maps implemented by partitions of unity {x
j
} of grade 1 are considered, resembling the “canonical endomorphism” of the Cuntz algebras. The relationship between the Voiculescu
topological entropy of and the topological entropy of the associated subshift is studied. Examples where the equality holds are discussed among
Matsumoto algebras associated to non finite type subshifts. In the general case is bounded by the sum of the entropy of the subshift and a suitable entropic quantity of the homogeneous subalgebra. Both
summands are necessary.
The measure-theoretic entropy of , in the sense of Connes–Narnhofer–Thirring, is compared to the classical measure-theoretic entropy of the subshift.
A noncommutative analogue of the classical variational principle for the entropy is obtained for the “canonical endomorphism”
of certain Matsumoto algebras. More generally, a necessary condition is discussed. In the case of Cuntz–Krieger algebras an
explicit construction of the state with maximal entropy from the unique KMS state is done.
Received: 1 February 2000 / Accepted: 23 February 2000 相似文献
8.
J. A. Lay D. V. Fedorov A. S. Jensen E. Garrido C. Romero-Redondo 《The European Physical Journal A - Hadrons and Nuclei》2010,44(2):261-277
We investigate to what extent 18Ne can be descibed as a three-body system made of an inert 16O core and two protons. We compare to experimental data and occasionally to shell model results. We obtain three-body wave
functions with the hyperspherical adiabatic expansion method. We study the spectrum of 18Ne , the structure of the different states and the predominant transition strengths. Two 0+, two 2+, and one 4+ bound states are found where they are all known experimentally. Also one 3+ close to threshold is found and several negative-parity states, 1-, 3-, 0-, 2-, most of them bound with respect to the 16O excited 3- state. The structures are extracted as partial-wave components, as spatial sizes of matter and charge, and as probability
distributions. Electromagnetic decay rates are calculated for these states. The dominating decay mode for the bound states
is E2 and occasionally also M1 . 相似文献
9.
《Journal of Nonlinear Mathematical Physics》2013,20(1):50-53
Abstract We discuss stationary solutions of the discrete nonlinear Schrödinger equation (DNSE) with a potential of the ? 4 type which is generically applicable to several quantum spin, electron and classical lattice systems. We show that there may arise chaotic spatial structures in the form of incommensurate or irregular quantum states. As a first (typical) example we consider a single electron which is strongly coupled with phonons on a 1D chain of atoms — the (Rashba)–Holstein polaron model. In the adiabatic approximation this system is conventionally described by the DNSE. Another relevant example is that of superconducting states in layered superconductors described by the same DNSE. Amongst many other applications the typical example for a classical lattice is a system of coupled nonlinear oscillators. We present the exact energy spectrum of this model in the strong coupling limit and the corresponding wave function. Using this as a starting point we go on to calculate the wave function for moderate coupling and find that the energy eigenvalue of these structures of the wave function is in exquisite agreement with the exact strong coupling result. This procedure allows us to obtain (numerically) exact solutions of the DNSE directly. When applied to our typical example we find that the wave function of an electron on a deformable lattice (and other quantum or classical discrete systems) may exhibit incommensurate and irregular structures. These states are analogous to the periodic, quasiperiodic and chaotic structures found in classical chaotic dynamics. 相似文献
10.
The hypernucleus Be is investigated in an α-α-Λ three-body model using the Faddeev formalism. We use an α-α interaction in which the Pauli-forbidden
states are correctly taken into account and we employ some phenomenological potentials between the α and Λ particles. We obtained
two bound states for and , and three resonance states of . We studied the properties of these states by calculating the components and the expectation values of the potential for
each partial wave. It is found that a few channels dominate in the α (α, Λ) and states, so that the alpha-clusters or the 8Be core are still alive in the nucleus. In a case where the two alpha particles are fixed on an axis the contour plots of
the distribution of the Λ particle are shown. With the assistance of these plots one can visually understand that some of
them are shell-model-like states while others are well developed cluster-model-like states. For the structure of Be, it is concluded that the Λ particle is loosely coupled in S- and P-wave orbits about the 8Be(0+) and 8Be(2+) core states. Finally, we discuss a redundant state in the Faddeev amplitude which could arise from the treatment of symmetrization.
Received June 25, 1998; revised April 13, 1999; accepted for publication December 29, 1999 相似文献
11.
12.
We investigate electron transport inside a ring system composed of a quantum dot (QD) coupled to two Majorana bound states confined at the ends of a one-dimensional topological superconductor nanowire. By tuning the magnetic flux threading through the ring, the model system we consider can be switched into states with or without zero-energy modes when the nanowire is in its topological phase. We find that the Fano profile in the conductance spectrum due to the interference between bound and continuum states exhibits markedly different features for these two different situations, which consequently can be used to detect the Majorana zero-energy mode. Most interestingly, as a periodic function of magnetic flux, the conductance shows 2π periodicity when the two Majorana bound states are nonoverlapping (as in an infinitely long nanowire) but displays 4π periodicity when the overlapping becomes nonzero (as in a finite length nanowire). We map the model system into a QD–Kitaev ring in the Majorana fermion representation and affirm these different characteristics by checking the energy spectrum. 相似文献
13.
A. Hader A. Memsouk Y. Boughaleb 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(3):315-319
We have studied the scaling properties of diffusion fronts by numerical calculations based on the mean field approach in the
context of a lattice gas model, performed in a triangular lattice. We find that the height-height correlation function scales
with time t and length l as C(l, t) ≈l
α
f (t/l
α/β) with α = 0.62±0.01 and β = 0.39±0.02. These exponent values are identical to those characterising the roughness of the diffusion
fronts evolving through a square lattice [1,2], thus confirming their universality.
Received 14 November 2001 / Received in final form 20 April 2002 Published online 31 July 2002 相似文献
14.
T. Raddatz 《Zeitschrift fur Physik C Particles and Fields》1993,57(2):219-224
Mass gaps and wave functions in (2+1)-dimensionalSU (2) lattice gauge theory (no quarks) are investigated. Starting with lattice Hamiltonians possessing exactly known ground states and the correct naive continuum limit, it is possible to reach the very deep weak-coupling region. Using variational approximation and rescaling all parameters with the help of the dimensionful coupling constantg 2, we gain a formulation that is independent of the special choice of the Hamiltonian in the weak-coupling limit. The mass gap can be calculated and a kind of wave function for excited states obtained. 相似文献
15.
A. P. Chetverikov W. Ebeling M. G. Velarde 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(1):87-99
We investigate the onset and maintenance of nonlinear soliton-like excitations in chains
of atoms with Morse interactions at rather high densities, where
the exponential repulsion dominates.
First we discuss the atomic interactions and approximate the
Morse potential by an effective Toda potential with
adapted density-dependent parameters.
Then we study several mechanisms to generate
and stabilize the soliton-like excitations:
(i) External forcing: we shake the masses periodically, mimicking a
piezoelectric-like excitation, and delay subsequent damping
by thermal excitation;
(ii) heating, quenching and active friction:
we heat up the system to a relatively high temperature Gaussian
distribution, then quench to a low temperature,
and subsequently stabilize by active friction. Finally,
we assume that the atoms in the chain are ionized with free electrons able to move along the lattice.
We show that the nonlinear soliton-like excitations
running on the chain interact with the electrons. They
influence their motion in the presence of an external field creating dynamic
bound states (“solectrons”, etc.). We show that these
bound states
can move very fast and create extra current.
The soliton-induced contribution to the current
is constant, field-independent for a significant range of values when approaching the zero-field value. 相似文献
16.
Consider a linear autonomous Hamiltonian system with m time periodic bound state solutions. In this paper we study their dynamics under time almost periodic perturbations which
are small, localized and Hamiltonian. The analysis proceeds through a reduction of the original infinite dimensional dynamical
system to the dynamics of two coupled subsystems: a dominant m-dimensional system of ordinary differential equations (normal form), governing the projections onto the bound states and an infinite dimensional dispersive wave equation. The present work
generalizes previous work of the authors, where the case of a single bound state is considered. Here, the interaction picture
is considerably more complicated and requires deeper analysis, due to a multiplicity of bound states and the very general
nature of the perturbation's time dependence. Parametric forcing induces coupling of bound states to continuum radiation modes,
of bound states directly to bound states, as well as coupling among bound states, which is mediated by continuum modes. Our
analysis elucidates these interactions and we prove the metastability (long life time) and eventual decay of bound states
for a large class of systems. The key hypotheses for the analysis are: appropriate local energy decay estimates for the unperturbed
evolution operator, restricted to the continuous spectral part of the Hamiltonian, and a matrix Fermi Golden rule condition,
which ensures coupling of bound states to continuum modes. Problems of the type considered arise in many areas of application
including ionization physics, quantum molecular theory and the propagation of light in optical fibers in the presence of defects.
Received: 13 March 2002 / Accepted: 2 January 2003
Published online: 14 April 2003
Communicated by J.L. Lebowitz 相似文献
17.
The phase-shift-analysis data for the 3He4He scattering are analyzed using the effective-range theory, with the Coulomb interaction taken into account. We find both
the renormalized nuclear vertex constants for the vertex 7Be → 3He + 4He in the ground (3/2−) and in the first excited (1/2−) bound states of 7Be, and the corresponding asymptotic normalization constants of the radial wave functions in these states. The results obtained
can be used in an astrophysical S-factor calculation for radiative capture reaction 4He(3He, γ)7Be 相似文献
18.
拓扑绝缘体是当前凝聚态物理领域研究的热点问题.利用石墨烯材料的特殊能带特性来实现拓扑输运特性在设计下一代电子和能谷电子器件方面具有较广泛的应用前景.基于光子与电子的类比,利用光子拓扑材料实现了确定性界面态;构建了具有C_(6v)。对称性的类似石墨烯结构的的光子晶体复杂晶格;通过多种方式降低晶格对称性来获得具有C_(3v),C_3,C_(2v)和C_2对称的晶体,从而打破能谷简并实现全光子带隙结构;将体拓扑性质不同的两种光子晶体摆放在一起,在此具有反转体能带性质的界面上,实现了具有单向传输特性的拓扑确定性界面态的传输.利用光子晶体结构的容易加工性,可以简便地调控拓扑界面态控制光的传播,可为未来光拓扑绝缘体的研究提供良好的平台. 相似文献
19.
《中国科学:物理学 力学 天文学(英文版)》2020,(10)
Topological crystalline insulator(TCI) is one of the symmetry-protected topological states. Any TCI can be deformed into a simple product state of several decoupled two-dimensional(2 D) topologically nontrivial layers in its lattice respecting its crystalline symmetries called the layer construction(LC) limit. In this work, based on first-principles calculations we have revealed that both tetragonal LaSbTe(t-LaSbTe) and orthorhombic LaSbTe(o-LaSbTe) can be interpreted as stacking of 2 D topological insulators in each lattice space. The structural phase transition from t-LaSbTe to o-LaSbTe due to soft phonon modes demonstrates how the real space change can lead to the modification of topological states. Their symmetry-based indicators and topological invariants have been analyzed based on LC. We propose that LaSbTe is an ideal example demonstrating the LC paradigm, which bridges the crystal structures in real space to the band topology in momentum space. 相似文献
20.
Peng-ming Zhang Xi-guo Lee Shao-feng Wu Yi-shi Duan 《International Journal of Theoretical Physics》2007,46(7):1753-1762
We study the wave dislocations with an induced gauge potential. The topological current characterized the wave dislocations
is constructed with the dual of Abelian gauge field. And the topological charges and locations of the wave dislocations are
determined by the φmapping topological current theory. Furthermore, it is shown that the knotted wave dislocations can be
described with a Hopf invariant in the wave field. At last we discussed the evolution of the knotted wave dislocations.
PACS 02.10.Kn, 02.40.-k, 11.15.-q 相似文献