Nonclassicality of photon-modulated spin coherent states in the Holstein-Primakoff realization

Two new photon-modulated spin coherent states (SCSs) are introduced by operating the spin ladder operators J ± on the ordinary SCS in the Holstein-Primakoff realization and the nonclassicality is exhibited via their photon number distribution, second-order correlation function, photocount distribution and negativity of Wigner distribution. Analytical results show that the photocount distribution is a Bernoulli distribution and the Wigner functions are only associated with two-variable Hermite polynomials. Compared with the ordinary SCS, the photon-modulated SCSs exhibit more stronger nonclassicality in certain regions of the photon modulated number k and spin number j, which means that the nonclassicality can be enhanced by selecting suitable parameters.

Engineering the magnetism of nanographene via co-depositing hetero precursors

The magnetism of carbon nanomaterials is dominated by the structure of its carbon skeleton. However, the magnetism engineering is hindered due to finite precursors. Here, we develop a new strategy to engineer the magnetism of nanographene through hetero-coupling two different precursors on Au(111) surface by using low-temperature bond-resolved scanning tunneling microscopy and scanning tunneling spectroscopy, combined with spin-polarized density functional theory calculations. Our results demonstrate that two homo-coupled products host close shell structure along with defects inducing magnetic one with the total spin number S = 1/2. Upon simultaneous depositing with another precursor, two hetero-coupled products switch to magnetic structure with the S = 1/2 and S = 1 resulting from carbon skeleton transformation. Our results provide a valid way via inducing different molecular precursors to engineer the magnetism of carbon nanomaterials, which could be extended in other magnetic materials instruction.

Impurity-Induced Spin-State Crossover in La0.8Sr0.2Co1−xAlxO3

We have prepared a set of polycrystalline samples of La 0.8 Sr 0.2 Co 1 − x Al x O 3 ( 0 ≤ x ≤ 0.2 ), and have measured the magnetization as functions of temperature and magnetic field. We find that the average spin number per Co ion ( S Co ) evaluated from the room-temperature susceptibility is around 1.2–1.3 and independent of x. However, we further find that S Co evaluated from the saturation magnetization at 2 K is around 0.3–0.7, and decreases dramatically with x. This naturally indicates that a significant fraction of the Co 3 + ions experience a spin-state crossover from the intermediate- to low-spin state with decreasing temperature in the Al-substituted samples. This spin-state crossover also explains the resistivity and the thermopower consistently. In particular, we find that the thermopower is anomalously enhanced by the Al substitution, which can be consistently explained in terms of an extended Heikes formula.

QUASINORMAL MODES OF THE SCHWARZSCHILD BLACK HOLE WITH ARBITRARY SPIN FIELDS: NUMERICAL ANALYSIS

The quasinormal modes (QNMs) associated with the decay of massless arbitrary spin fields around a Schwarzschild black hole are investigated by using the continued fraction method in a united form and their universal properties are found. It is shown that these QNMs become evenly spaced for large angular quantum number l (for the boson perturbations) and j (for the fermion perturbations) and the spacing is given by [Formula: see text] which is independent of the spin number s and overtone number n, and in the complex plane they have an interesting trend which depends on n before they become the same value with the increasing l (or j). The distribution of the QNMs with arbitrary spin fields for large values l (or j) and small n can be expressed as [Formula: see text]. It is also shown that the angular quantum number has the surprising effect of increasing real part of the QNMs, but it almost does not affect the imaginary part, especially for the lowest lying mode. In addition, the spacing for imaginary part of the QNMs at high overtones is equidistant and equals to -i/4M, which is independent of l (or j) and s.