Anomalous Magnetic Contribution Research Articles

Anomalous thermal expansion in intermediate valence compound Ce2Ni3Si5

The linear thermal expansion coefficients in the intermediate valence system Ce2Ni3Si5 were determined along the main crystallographic directions by means of neutron diffraction in the temperature range 10–300 K. The anomalous contribution to thermal expansion due to valence instabilities of cerium was estimated by employing the virtual mix approach. The magnitude of the anomalous magnetic contribution to the volume coefficient of thermal expansion in this intermetallic system is about 1.2× 10−5 K−1. The observed effect is caused by a strong temperature dependence of the degree of the partial delocalization of the cerium 4f electrons in the intermediate valence regime. The effective Kondo temperature of Ce2Ni3Si5 TK = 140 К obtained in the present work is in a very good agreement with the earlier estimates based on the temperature dependences of the macroscopic magnetic and thermodynamic properties.

Anomalous Magnetic Contributions to Hall Effect in Ho0.5Lu0.5B12

Anomalous Magnetic Contributions to Hall Effect in Ho_0.5Lu_0.5B₁₂

Analysis of anomalous negative magnetic contribution to thermal expansion in Sm0.80B6 and pseudobinary compounds Sm1−xLaxB6 (x = 0, 0.10, 0.22, 0.50)

This study is the first attempt to apply the two-level Weiss model for the invar alloy to intermediate-valence samarium systems. This model is instrumental in giving a quantitative characterisation of the anomalous magnetic contribution to the coefficient of thermal expansion (CTE) of Sm0.80B6 and Sm1−xLaxB6 (x = 0, 0.10, 0.22, 0.50). A good agreement between the experimental and calculated magnetic contributions to the CTE is achieved for Sm0.78La0.22B6 over the temperature range from 0 K to 210 K. In other systems, a good fit is obtained over shorter temperature ranges. The model parameters and the dependence of the CTE minimum on the level of lanthanum doping in SmB6 are presented.

Heat capacity and critical behavior of hexagonalYMnO3

We report heat capacity $({C}_{p})$ measurements on high-quality single crystals of hexagonal $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$, a ferroelectric and frustrated triangular antiferromagnetic (AF) compound. The obtained values of the critical exponent $\ensuremath{\alpha}$ and amplitude ratio ${A}^{+}∕{A}^{\ensuremath{-}}$ for the AF transition are in good agreement with the standard three-dimensional Heisenberg universality class, and not with a chiral universality class associated with the 120\ifmmode^\circ\else\textdegree\fi{} spin structure. The low-temperature ${C}_{p}$ deviation from the Debye law can be adequately fitted with a single Einstein contribution, indicating that there is no evidence of the anomalous magnetic contributions reported earlier. We also suggest that there is no intrinsic linear term in the low-temperature ${C}_{p}$. These results are consistent with conventional long-range AF ordering in $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$.

Interplay between magnetism, charge localization, and structure inSr14−xCaxCu24O41

Measurements of the thermal expansion of ${\mathrm{Sr}}_{14\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{Cu}}_{24}{\mathrm{O}}_{41}$ $(0l~xl~12)$ single crystals were performed. At low temperature and small $x$ we observe anomalous magnetic contributions which are ascribed to the formation of the spin gap state in the chains. From our data we derive a positive pressure derivative of the spin gap and we show that the dimers are formed by next nearest Cu neighbors. Additional anomalous contributions to the thermal expansion are attributed to a low-dimensional charge order occurring at higher temperature. The relevance of the charge order for the spin gap formation is discussed.

Semilocal nontopological vortices in a Chern-Simons theory.

We show the existence of self-dual semilocal nontopological vortices in a ${\mathrm{\ensuremath{\Phi}}}^{2}$ Chern-Simons (CS) theory. The model of scalar and gauge fields with a SU(2${)}_{\mathrm{global}}$\ifmmode\times\else\texttimes\fi{}U(1${)}_{\mathrm{local}}$ symmetry includes both the CS term and an anomalous magnetic contribution. It is demonstrated here that the vortices are stable or unstable according to whether the vector topological mass \ensuremath{\kappa} is less than or greater than the mass m of the scalar field. At the boundary \ensuremath{\kappa}=m, there is a two-parameter family of solutions all saturating the self-dual limit. The vortex solutions continuously interpolate between a ring-shaped structure and a flux tube configuration.

STABILITY OF NON-TOPOLOGICAL CHERN-SIMONS VORTICES IN A ϕ2-MODEL

We study the stability under small perturbations for the recently discovered self-dual non-topological vortices in a ϕ2 Abelian Chern-Simons (CS) theory. The solitons appear in the Bogomol'nyi limit of a model of scalar and gauge fields which includes both the CS term and an anomalous magnetic contribution. It is demonstrated here, that the vortices are stable or unstable according to whether the vector topological mass κ is less than or greater than the mass m of the scalar field. The interaction between vortices is determined as attractive for (m < κ) and repulsive for (m > κ).

Bogomol'nyi limit for nontopological solitons in a Chern-Simons model with anomalous magnetic moment.

We study an Abelian Chern-Simons (CS) model which includes both the CS term and an anomalous magnetic contribution. We find that, for a special relation between the CS mass and the anomalous magnetic coupling, the equations for the gauge fields reduce from second- to first-order differential equations. It is shown that charged vortices of finite energy exist. Furthermore, we show that nontopological solitons satisfy a set of Bogomol'nyi-type equations for a simple $(\frac{{m}^{2}}{2}){\ensuremath{\varphi}}^{2}$ potential, when $m$ and the topological mass are equal.