The Dy-Sc nitride clusterfullerene Dy2ScN@C80-Ih exhibits slow relaxation of magnetization up to 76 K. Above 60 K, thermally-activated relaxation proceeds via the fifth-excited Kramers doublet with the energy of 1735 ± 21 K, which is the highest barrier ever reported for dinuclear lanthanide single molecule magnets.

1 Introduction The magnetocaloric effect [1,2] is the basis of an energy-efficient refrigeration technology, which has the potential to reduce the energy consumption of air conditioners, refrigerators and other domestic and industrial cooling applications [3]. The most promising magnetocaloric materials exhibit first-order magnetostructural or magnetovolume transitions, which lead to high adiabatic temperature changes in response to a changing external magnetic field. The transition temperatures of these firstorder transitions can be shifted towards room temperature by means of hydrogenation or doping [4]. However, large entropy and temperature changes can only be maintained if the first-order nature of the transition is kept [4].However, it has been shown for first-order-type magnetocaloric La(Fe,Si) 13 that when measuring the adiabatic temperature change ΔT ad , one needs to carefully distinguish between the first field cycle, which delivers a high adiabatic temperature change of ΔT ad = 7 K, and following cycles, in which it is reduced to ΔT ad = 5.8 K [5]. Similar findings have been reported for magnetocaloric Heuslers

We report the processing, analysis and testing of magnetocaloric composite materials consisting of La-Fe-Co-Si particles of various size fractions and a polymer matrix. All of the composites have working temperatures close to room temperature. The composites were pressed into thin plates, a geometry favorable for testing the composites in an active magnetic regenerator (AMR). In order to investigate the influence of particle size and binder type (epoxy), eight different epoxy-bonded La-Fe-Co-Si plates were made and analyzed. We found that the higher filling factor that can be achieved by using a mixture of several particle size fractions has beneficial influence on the thermal conductivity. Tests in the AMR revealed that a maximum temperature span of approximately T = 10 K under magnetic field change of 0H = 1.15 T can be obtained at no cooling load conditions. The stability of the measured T values and the mechanical integrity of sample after cyclic application of a magnetic field have been monitored for 90.000 cycles and showed no significant changes. We therefore conclude that epoxy-bonded La-Fe-Co-Si magnetocaloric composites have good magnetocaloric properties at low material-processing costs and hence represent a competetive way to produce magnetocaloric materials to be used in AMR.

Reported here are the results and their analysis from our detailed investigations of the effects of Cu doping ([Formula: see text]) on the electronic structure and magnetic properties of the spinel [Formula: see text]O. A detailed comparison is given for the [Formula: see text] and [Formula: see text] cases for both the bulk-like samples and nanoparticles. The electronic structure determined from x-ray photoelectron spectroscopy and Rietveld analysis of x-ray diffraction patterns shows the structure to be: ([Formula: see text]) [Formula: see text] [Formula: see text] [Formula: see text]] [Formula: see text] i.e. [Formula: see text] substitutes for [Formula: see text] on the octahedral B-sites. For the bulk samples, the ferrimagnetic [Formula: see text] K for [Formula: see text] is lowered to [Formula: see text] K for the [Formula: see text] sample, this decrease being due to the effect of Cu doping. For the nanosize [Formula: see text] ([Formula: see text]) sample, the lower [Formula: see text] K ([Formula: see text] K) is observed using [Formula: see text] analysis, this lowering being due to finite size effects. For [Formula: see text], fits of dc paramagnetic susceptibility data of [Formula: see text] versus T in nanosize samples to the Néel expression are used to determine the exchange interactions between the A and B sites with exchange constants: [Formula: see text] K (4.1 K), [Formula: see text] K (16.3 K) and [Formula: see text] K (13.8 K) for [Formula: see text]. The temperature dependence of ac susceptibilities [Formula: see text] and [Formula: see text] at different frequencies shows that in bulk samples of [Formula: see text] and [Formula: see text], the transition at T is the normal second order transition. But for the nanosize [Formula: see text] and 0.2 samples, analysis of the ac susceptibilities shows that the ferrimagnetic transition at T is followed by a re-entrant spin-glass transition at lower temperatures [Formula: see text] K (138 K) for [Formula: see text] ([Formula: see text]). Analysis of the ac susceptibilities, [Formula: see text] and [Formula: see text], versus T data is done in terms of two scaling laws: (i) Vogel-Fulcher law [Formula: see text] [Formula: see text]; and (ii) power law of critical slowing-down [Formula: see text]. These fits confirm the existence of glassy behavior below T with the parameters [Formula: see text] (8.91), [Formula: see text] (9.6  ×  10[Formula: see text]) and [Formula: see text] K (∼138 K) for the samples [Formula: see text] (0.2), with similar results obtained for other samples. The linear behavior of the peak maximum in [Formula: see text] versus [Formula: see text] (AT-line) further supports the existence of glassy states in nanosize samples. For [Formula: see text], the temperature and composition dependence of the hysteresis loop parameters are investigated; all the samples with x  ⩾  0.1 have the coercivity H and remanence [Formula: see text]. Since the results reported here in these nanostructures are significantly different from those in bulk [...

We report a detailed single-crystal and powder neutron diffraction study of Co2TiO4 and Co2SnO4 between the temperatures 1.6 K and 80 K to probe their spin structures in the ground state. For both compounds the strongest magnetic intensity was observed for the (111)M reflection due to ferrimagnetic ordering, which sets in below TN = 48.6 K and 41 K for Co2TiO4 and Co2SnO4, respectively. An additional low intensity magnetic reflection (200)M was noticed in Co2TiO4 due to the presence of an additional weak antiferromagnetic component. Interestingly, from both the powder and the single-crystal neutron data of Co2TiO4 we noticed a significant broadening of the magnetic (111)M reflection, possibly results from the disordered character of the Ti and Co atoms on the B site. Practically, the same peak broadening was found for the neutron powder data of Co2SnO4. On the other hand, from our single-crystal neutron diffraction data of Co2TiO4 we found a spontaneous increase of particular nuclear Bragg reflections below the magnetic ordering temperature. Our data analysis showed that this unusual effect can be ascribed to the presence of anisotropic extinction, which is associated to a change of the mosaicity of the crystal. In this case it can be expected that competing Jahn-Teller effects act along different crystallographic axes can induce anisotropic local strain. In fact, for both ions Ti 3+ and Co 3+ the 2tg levels split into a lower dxy level and yields a higher two-fold degenerate dxz/dyz level. As a consequence, one can expect a tetragonal distortion in Co2TiO4 with c/a < 1, which could not significantly detected in the present work.

The structural, magnetic, and magnetocaloric properties of epitaxial Ni-Co-Mn-Al thin films with different compositions have been studied. The films were deposited on MgO(001) substrates by co-sputtering on heated substrates. All films show a martensitic transformation, where the transformation temperatures are strongly dependent on the composition. The structure of the martensite phase is shown to be 14M. The metamagnetic martensitic transformation occurs from strongly ferromagnetic austenite to weakly magnetic martensite. The structural properties of the films were investigated by atomic force microscopy and temperature dependent x-ray diffraction. Magnetic and magnetocaloric properties were analyzed using temperature dependent and isothermal magnetization measurements. We find that Ni 41 Co 10.4 Mn 34.8 Al 13.8 films show giant inverse magnetocaloric effects with magnetic entropy change of 17.5 J kg −1 K −1 for μ 0 H = 5 T.

We demonstrate laser control of high-voltage discharges over a gap of 1.2 m filled with a dense water cloud. Self-guided filaments generated by ultrashort laser pulses are transmitted through the cloud and ionize a continuous plasma channel. The cloud typically reduces the discharge probability in given experimental conditions by 30%, but has almost no influence on the threshold required to trigger single discharge events, both in electrical field and laser energy. This result is favorable for real-scale lightning control applications.

This report introduces both synthesis and in vitro biological behaviour of dual magnetic-fluorescent silica nanoparticles.