Valence,electronic specific heat and magnetic susceptibility of alpha-cerium

A sixfold degenerate Anderson Hamiltonian, which includes the Coulomb repulsion between localized and band states in the mean field approximation following Ramírez and Falicov, is treated in the limit of infinitely correlated 4? states and to second order in the mixing parameter. Assuming a line width Γ ≈ 0.02eV we obtain at low temperatures and 11 kbar, a valency of 3.76 and sizeable contributions from the 4? levels to the electronic specific heat and magnetic susceptibility of alpha Ce. Thus we show, that the highly correlated picture necessary to the explanation of the alpha—gamma transition by Ramírez and Falicov needs not to be abandoned in order to explain the anomalies in alpha Ce.     

NMR,magnetic susceptibility and specific heat of CrAl7

The temperature dependence of the magnetic susceptibility, Knight shift and specific heat for the compound CrAl₇ have been measured. These measurements point out that, at the temperature around T_N ≈220 K the compound CrAl₇ presents a second order phase transition from the electron itinerant antiferromagnetism state to the paramagnetic state. The NMR and magnetic susceptibility measurements are correlated and the results are discussed in terms of the electron itinerant antifer-romagnetism and rigid band models. For the temperature independent-term of the susceptibility all the contributions are given.     

Magnetic moments contribution to the specific heat and susceptibility of heavy fermion system

In non-magnetic heavy fermion systems, valence fluctuations prevent formation of long-range magnetic correlations. The RKKY exchange fields fluctuate due to f-electron transfers to the conduction band. To simulate these processes, we use the Ising-type model with fluctuating fields. The linear temperature dependence of the specific heat and temperature independence of susceptibility suggest that the f-electron contribution to these quantities can be considered as complementary to the one originating from Kondo resonance.     

Magnetic susceptibility and specific heat of intermediate valence Tm compounds

We calculate the static magnetic susceptibility and specific heat of a model periodic system, with valence fluctuations between two magnetic configurations, intended to describe intermediate valence Tm compounds.These properties are derived from an expression for the free energy obtained using the coherent potential approximation, which properly takes into account the correlation energy and the configurational entropy.The resulting properties are in reasonable agreement with the experimental data. Unlike the results found in the commonly studied Anderson model, we find divergences in the magnetic susceptibility that indicate the onset of ferromagnetic order for some values of the model parameters.     

Superconductivity and electronic specific heat in V-Mo system

The parameters of superconductivity and specific heat are determined from the low temperature specific heat measurements of V_(1−x)Mo_x (0 ⩽ x ⩽ 1) solid solutions. The coefficient of electronic specific heat γ decreases with increasing Mo concentration and shows a minimum around 80 at. %Mo. Debye temperature θ_D varies slightly over the whole composition range. The superconducting transition temperature T_c also decreases with increasing Mo concentration. The variation of T_c is explained by the variation of γ and discussed in terms of the band structure.     

The determination of magnetic susceptibility anisotropies from quadrupolar interactions in NMR

Magnetic susceptibility anisotropies are reported for acenaphthene, fluorene, biphenyl, and porphin. They have been derived from the quadrupolar line splittings in the ²H NMR spectra of the compounds in a field of 9.3 T. The magnetic field dependence of these splittings has been studied by additional experiments at 11.6 T for the molecules naphthalene, triphenylene, pyrene, acenaphthene, anthracene, and fluorene. A strong solvent dependence of the magnetic field effect on the ²H spectrum of nitrobenzene at 11.6 T has been detected.     

Novel phase transitional properties on specific heat of diluted magnetic semiconductor

Three types of phase transitions in diluted magnetic semiconductor, first-order, second-order and mixed-order, are found in theory. Especially the mixed-type transition shows two-steps transition and novel specific heat property. Specific heat properties disclose a possible meta ferromagnetic phase confirmed by the experimental qualitative result.     

A new scaling analysis of the susceptibility and the specific heat of the non-Fermi liquid system with and 0.5

The usual scaling equations at a phase transition, employed out of their usual validity range, with T_c a negative constant, fit properties observed in correlated electron systems with unmatched accuracy. We illustrate this behavior with our data in Ce(Ru_1-xRh_x)₂Si₂ for x = 0.4 and 0.5 and comment these results and what they imply physically. Received 22 June 1998 and Received in final form 29 September 1998     

Effect of thallium on magnetic susceptibility of arsenic sulphides

Magnetic susceptibility was studied of samples of Tl_2xAs₂S_3+x and Tl_2xAs₂S₄ series where 0x1 differing in abundance of bonds in structural units. Absolute value of specific magnetic susceptibility decreases with increasing thallium content. Separation of susceptibility in dia- and paramagnetic parts made it possible to refer to the correlation of absorption edge position and paramagnetic susceptibility component.     

Effect of magnetic,crystal field and exchange interactions on graphene system: a Monte Carlo study

In this article, we employ the classical Monte Carlo approach to study the magnetic properties of graphene system. We analyze the ground-state phase diagrams in the presence of external magnetic and crystal fields under effect of the exchange interactions. The critical temperature is deduced. It is proven that the model exhibits the second-order phase transitions at the transition temperature. The total magnetization with the exchange interactions has studied under the temperatures effect. The total magnetization with the crystal field has been established under effect of exchange interactions and temperatures effect. The magnetic hysteresis cycles of graphene system is deduced under effect of temperatures and crystal field. The observations are in good agreement with related experiments and the other theoretical results. It is proven that the graphene system exhibits the superparamagnetic at the transition temperature and a specific value of reduced crystal field.     

Magnetic field dependence of the impurity specific heat in dilute magnetic alloys

Using a trial sunction scheme at finite temperature, the impurity specific heat has been calculated in terms of the Wolff model with an external magnetic field. When local moments exist, the magnetic field effect is drastic under accessible experimental condition. In the absence of local moments, the specific heat is practically field independent. If accurate specific heat can be measured, it provides a new method to detect local moments in dilute magnetic alloys.     

Exchange interactions in Ti2Cl3- 9 and the magnetic susceptibility tensor

Calculated exchange interactions in Ti²Cl^3- ₉ by the CASSCF method are combined with parametric expressions of metal-centred spin—orbit coupling and Zeeman splittings to predict the temperature dependence of the magnetic susceptibility tensor between 0 and 300 K. The results correctly reproduce the experimental anisotropy at 0 K, the onset of the magnetization and the slope of the susceptibility curve. The discussion confronts the theoretical treatment with existing semi-empirical magnetic models. A ¹A′₁(a × a) → 1E′(a × e) assignment is proposed for the weak absorption feature in the infrared reflectance spectrum.     

Concentration dependence of magnetic susceptibility for the system of dilute magnetic impurities

The concentration dependence of the magnetic susceptibility for the system of randomly distributed dilute magnetic impurities in a d-dimensional metal or on a metal surface is studied at zero-temperature under the mean-random-field approximation. It is shown that, if the amplitude of the RKKY-type interaction between the magnetic impurities behaves like $\text{1}\text{r}{}^{\mathrm{n}}$ at a large distance r, the susceptibility is proportional to $\text{c}{}^{\mathrm{<mtext>1?(</mtext><mtext>n</mtext><mtext>d</mtext><mtext>)</mtext>}}$, where c is the concentration of the magnetic impurities.     

Specific heat and magnetic susceptibility at low temperature of two conductive TCNQ salts

The specific heat measurements between 1.4 and 4.4 K of acridinium (TCNQ)₂ and quinolinium (TCNQ)₂ salts show up a linear component; moreover, in presence of a strong magnetic field (H = 40kG), an artificial Schottky anomaly is revealed. Magnetic susceptibility experiments confirm the simultaneous existence of charge carriers, in a partially filled energy band, and localized paramagnetic centers. A standard energy band model is proposed to interpret these two properties.     

Collapse of the magnetic ordering and structural anomalies in the U La S system: neutron diffraction and specific heat measurements

We report specific heat and neutron diffraction measurements of seven samples in the solid solution system U_xLa_1-xS. All samples have the simple fcc NaCl crystal structure. Both specific heat and neutron diffraction confirm the suggestion from the earlier magnetic measurements that the ferromagnetism disappears abruptly at 0.57. Near there is a doubling of the electronic contribution to the specific heat, as compared to the value of 23 mJ mol^-1K^-2 in pure US. Around the widths of the nuclear Bragg peaks show a considerable broadening, as well as anomalies in the mean lattice parameter, as compared to those expected from Vegard's law. A preliminary analysis suggests this broadening may be due to a loss of long range lattice order near . However, these changes are independent of temperature, so that further experiments are necessary before they can be associated with the changes in magnetic behavior at . Received 18 September 1998