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The Ni50Mn37AlxSb13-x (x=0, 1, 3 and 5) alloys were prepared by tri-arc melting technique. The replacement of Sb by Al increases the martensitic transformation temperature (TM) as well as ferromagnetic to paramagnetic transformation temperature (=start_CONVERSION_=TCA=start_CONVERSION_=) within the austenite phase. The increase in TM is found to due to the enhancement of hybridization between 3d states of Ni and Mn atoms. We also observed a large exchange bias field (HEB) of 470Oe for x=0 and it decreases with the Al concentration for field cooled (FC) magnetic hysteresis loop. A large magnetic entropy change (ΔSM) of 10J/kg-K is found for x=1 alloy under a field change (ΔH) of 50kOe and it decreased for further higher concentration of Al doping. The possible reasons for observed behaviors are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The structure, Raman spectroscopy, magnetization, and dielectric properties of delafossite-type oxide CuCr1−x Al x O2 have been characterized. It was found that Al substitution generates an anisotropic effect on the structure, besides magnetic dilution. The temperature dependence of all samples exhibits paramagnetic behavior at high temperature. Above x=0.2 the ferromagnetic transition at 120K disappears. It is argued that Al substitution destabilizes the antiferromagnetic order of Cr3+ ions and modulates the spin configuration, leading to a weak ferromagnetism. The coupling between the magnetic order and ferroelectric order is also characterized. [Copyright &y& Elsevier]

Abstract: We investigate the formation of ferrihydrite nanoparticles (NPs) by hydrolysis of the Fe(III) alkoxide Fe(OtBu)3. Controlled amounts of water, up to 3.0vol%, were added to the precursor solution yielding a series of hydrolyzed samples ranging from P0.0 (the unreacted precursor) to P3.0. X-ray diffraction (XRD) analysis evidenced the formation of high-crystalline ferrihydrite NP in sample P3.0, with grain size estimate of about 3.2nm. The transition from the molecular precursor to the formation of crystalline magnetic NPs was followed through magnetization measurements M(T) and M(H), as well as Mössbauer spectroscopy (MS). M(T) measurements indicate a paramagnetic (PM) behavior for sample P0.0, characteristic of binuclear Fe–O–Fe units, which evolves to a superparamagnetic (SPM) behavior, with an energy barrier for the blocking process estimated for sample P3.0 as E a=4.9×10−21 J (E a/k B=355K), resulting in a high effective anisotropy constant K eff=290kJ/m3. Magnetization loops at 5K progressively change from PM-like to ferromagnetic-like shape upon increasing the hydrolysis process, although hysteresis (H c≈500Oe) only is apparent for P2.0 and higher. MS spectra at room temperature are PM/SPM doublets for all samples, while the MS spectra at T=4.2K reveal increasingly well-defined magnetic ordering as hydrolysis of the precursor stepwise progresses until well-crystallized ferrihydrite particles are formed. [Copyright &y& Elsevier]

Abstract: Temperature-dependent zero-, longitudinal- and transverse-field spectra have been recorded in nanometric obtained by mechanical alloying. The alloy comprises Fe(Cu) nanoparticles (5nm) in a Ag matrix formed by 16nm particles, as deduced from the Rietveld refinement of the X-ray diffraction pattern. The muon depolarization can be described by a Dynamical Lorentzian Kubo–Toyabe function. This is in agreement with a high degree of interparticle dipolar interactions, giving rise to a cluster spin glass-like behavior below 100K. The intra particle interactions are also probed by the , and influence the thermal variation of the static width. [Copyright &y& Elsevier]

Abstract: An analytic expression is obtained for the point-function demagnetization tensor of the uniformly magnetized equilateral triangular prism element. This result can be used to improve the precision in 3D finite element micromagnetic models, especially for complex boundary geometric shapes. The corresponding magnetometric demagnetization tensors and demagnetization factors are calculated with the expression. The demagnetization field is discussed at various aspect ratios with magnetization perpendicular to the triangle plane. [Copyright &y& Elsevier]

Abstract: The paramagnetic and the one-step replica-symmetry-breaking spin-glass solutions of a p-spin-glass model in the presence of a transverse field are studied in the neighborhood of the phase transition curve. Two qualitatively different regions are found in the phase diagram. For a transition temperature higher than a certain value , the thermodynamic transition is of second order, otherwise it is of first order with latent heat. The temperature is joined to a point in the phase diagram where a transition between two paramagnetic solutions happens. A discussion about the order of the thermodynamic-phase transition in the quantum random orthogonal model is presented. [Copyright &y& Elsevier]

Nanocrystalline nickel–zinc, zinc–manganese, and nickel–manganese ferrites synthesized by reverse micelle synthesis technique were characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction, and the magnetic behavior studied by Superconducting Quantum Interference Device. The mixed (Ni–Zn, Zn–Mn, and Ni–Mn) ferrites exhibit blocking temperatures of 11, 20, and 15 K, respectively. The small differences in the blocking temperatures are attributed to the magnetocrystalline anisotropy and L–S coupling. The saturation magnetization of nanocrystalline Ni–Zn, Zn–Mn, and Ni–Mn at 300 K was 4.5, 9, and 7 emu/g, respectively, and at 2 K was 15, 19, and 14 emu/g, respectively. The lower saturation magnetization of the nanocrystalline ferrites compared to their bulk counterparts is attributed to the core–shell morphology of the particles consisting of ferromagnetically aligned core spins and a spin-glass-like surface layer. [Copyright &y& Elsevier]

Abstract: In the A-site spinels (, Fe, Co) the A-site sublattice is subjected to strong frustration, putting all three compounds on the verge between long-range and short-range magnetic order. The spectra of the three compounds show two signals at all temperatures examined and a dramatic change in spectral shape at characteristic temperatures. Above this temperature, one signal (slowly relaxing) is typical for free paramagnetic spins, the other (fast relaxing) for highly correlated paramagnetic spins. For the ratio of their intensities is 1:3 independent of temperature and the spectral change occurs around 40K ( from neutron data) where the strongly correlated fraction enters into long-range order and the free paramagnetic fraction into a glassy spin state. For or Fe, the free paramagnetic fraction increases from to 85% with rising temperature. At the cusp temperatures observed in magnetization (5 or 12K) the dominating, highly correlated paramagnetic fraction turns into a dynamic short-range ordered magnetic ground state. In all three compounds substantial local spin disorder and persistent spin fluctuations characterize their magnetic ground states, typical features of highly frustrated magnets. [Copyright &y& Elsevier]

Abstract: We present data recorded on a newly prepared sample of the geometrically frustrated magnetic material . These data confirm previously published results and clearly show that there is a dynamical component in the ground state. This seems in contrast to the result of the linear spin-wave calculation of A.G. Del Maestro and M.J.P. Gingras which predicts the spin-waves to be gapped over the whole first Brillouin zone with a gap larger than about in temperature scale. The measured high-temperature paramagnetic spin dynamics is understood with a simple model. The conditions for observing a spontaneous magnetic field and a finite relaxation rate at low temperature are discussed in terms of the properties of a function which measures the density of fluctuation modes. [Copyright &y& Elsevier]

Abstract: AC-susceptibility measurements for HoCo3B2 show paramagnetism below room temperature and a small, and large anomalies at 150 and 10K, respectively. Neutron powder diffraction measurements show a ferromagnetic order below 10K, where the ferromagnetic Ho and Co sublattices are ferromagnetically coupled. The magnetic axis direction is perpendicular to the c axis. The observed magnitudes of the magnetic moments at 4.5K are 5.08(4) and 0.11(2) for Ho and Co, respectively. No long range magnetic order was detected above 10K. [Copyright &y& Elsevier]

Abstract: We report on the rare-earth valence and paramagnetic properties of Ce1− z Yb z Fe4Sb12, Ba y Fe4Sb12 and La y Fe4Sb12. Yb valence decreases from 2.7 for for whereas Ce is always trivalent. The dominant character of the magnetic interaction changes from ferromagnetic with divalent filler to antiferromagnetic with trivalent filler. The paramagnetic properties are dominated by the delocalized electrons of [Fe4Sb12] with a constant contribution close to 3.2μ B (f.u.)−1. [Copyright &y& Elsevier]

Abstract: We present the first DCA results for the 2D Hubbard model obtained with a suitably extended version of Wilson''s NRG. We discuss the rôle of non-local fluctuations on the spectral properties at for half-filling. In particular, we find that the system is a paramagnetic insulator for all . [Copyright &y& Elsevier]

The magnetic scattering in the paramagnetic phases of MnAs has been investigated in a spin polarised neutron scattering experiment. The magnetic correlations are found to indicate ferromagnetic short-range order which persists in both the orthorhombic as well as the high temperature hexagonal modification of MnAs. In particular, the unusual magnetic properties of the orthorhombic phase, as revealed by magnetisation measurements, are not mirrored in the magnetic scattering results which have been obtained in an almost zero external field experiment. The magnitude and the scattering vector dependence of the magnetic moment do not change as a function of temperature. It is argued that the unusual temperature dependence of the magnetic susceptibility is a phenomenon induced by the application of an external magnetic field and arises due to a coupling of magnetic and lattice degrees of freedom. [Copyright &y& Elsevier]

Cobalt ferrite powder has been synthesized by the forced hydrolysis method in 1,2-propanediol. The particles, having a cubic spinel structure, are nanocrystallites with a mean diameter of 4 nm with almost equiaxial shapes and a narrow size distribution. These particles are superparamagnetic at room temperature and ferrimagnetic at temperatures below the blocking temperature of about 180 K. A remarkable shift of the blocking temperature with frequency was observed in the AC susceptibility measurements. The calculated value of anisotropy constant at 0 K, KA(0)=5.36×107 erg/cm3, is higher than that in the bulk material. The saturation magnetization and the coercivity measured at 5 K are 75 emu/g and 10.3 kOe, respectively. [Copyright &y& Elsevier]

Abstract: Ultrathin Al films with an array of nano-sized holes are fabricated by quench-condensing Al near 20K on the surface of alumina membranes with a honeycomb pore structure. We describe this system as an experimental realization of a tunable washboard potential for studying the dynamics of vortices in the zero-temperature limit. We have observed large resistance fluctuations when a dc bias current is applied near the spin-paramagnetic limit. [Copyright &y& Elsevier]

Abstract: Precision measurements of charge transport parameters and magnetization have been carried out on the high-quality single crystals of CeB6 at temperatures 1.8–300K. It is shown that in the temperature interval of 5K