even though these compounds are most prone to such drawbacks, is the negative role of hysteresis. Since all MCE applications have a cyclic character, one of the main pre-conditions is to ensure a total (or at least partial) reversibility of the effect when either fi eld or temperature oscillations are applied. From a material point of view, this means keeping the fi eld or thermal hysteresis that could occur as small as possible. A second drawback of G-MCE materials is related to their mechanical stability. FOTs bring not only sharp magnetization jumps but also discontinuities of other physical parameters, including the unit cell. This "structural" part can have manifold aspects: symmetry breaking or cell-volume or lattice-parameter changes. The most dramatic for the stability of polycrystalline bulk samples turns out to be the cell-volume change. During thermal or magnetic fi eld cycles, the strains generated by a volume change may cause fractures or even destruction of the bulk piece, which severely hinders the applicability of these materials. Technical solutions can be used to overcome this problem, for instance by embedding the MCE material in a resin or by a porous shaping. [ 18 ] However, in such cases the MCE is "diluted", which is not satisfactory since the gap of the magnet is not effi ciently used and the thermal conductivity governing the heat transfer is decreased. Bulk G-MCE materials with a good mechanical stability should remain the preferred solution. Finally, to allow large-scale applications, a last requirement that should be borne in mind is that the MCE material must consist of elements that are available in large amounts, are not expensive, and are not classifi ed as toxic.In this context, the MnFe(P, x ) system appears to be an ideal playground. This material family is derived from the Fe 2 P compound, a prototypical example known for a long time to exhibit a sharp but weak (the latent heat L is only 0.25 kJ kg −1 ) FOT with a Curie temperature ( T C ) of 217 K. [ 19 ] In this hexagonal system, the Fe atoms occupy two inequivalent atomic positions referred to as 3f (in a tetrahedral environment of non-metallic atoms) and 3g (pyramidal). An intriguing aspect is the disappearance at T C of the magnetic moments of the iron atoms at the 3f sites, whereas there is only a limited decrease of the moments at the 3g site. This theoretical prediction has led to a cooperative description of the FOT that links the loss of longrange magnetic order at T C with the loss of the local moments at the 3f site. [ 20 ] This mechanism has recently been proposed to be the origin of the G-MCE observed in MnFe(P,Si). The disappearance of the magnetic moments is ascribed to a conversion from non-bonding d electrons to a distribution with pronounced hybridization with the surrounding Si/P atoms. [ 11 ] A practical consequence is that the FOT mechanism can be expected to be highly sensitive to substitutions at the nonmetallic site. In the present work, precisely this approach has been used to solve three problems of ...

Trioxaquines are antimalarial agents based on hybrid structures with a dual mode of action. One of these molecules, PA1103/ SAR116242, is highly active in vitro on several sensitive and resistant strains of Plasmodium falciparum at nanomolar concentrations (e.g., IC 50 value ‫؍‬ 10 nM with FcM29, a chloroquineresistant strain) and also on multidrug-resistant strains obtained from fresh patient isolates in Gabon. This molecule is very efficient by oral route with a complete cure of mice infected with chloroquine-sensitive or chloroquine-resistant strains of Plasmodia at 26 -32 mg/kg. This compound is also highly effective in humanized mice infected with P. falciparum. Combined with a good drug profile (preliminary absorption, metabolism, and safety parameters), these data were favorable for the selection of this particular trioxaquine for development as drug candidate among 120 other active hybrid molecules.curative drug ͉ malaria ͉ Plasmodium ͉ heme ͉ alkglation

No abstract

We study the spin Hall magnetoresistance effect in ferrimagnet/normal metal bilayers, comparing the response in collinear and canted magnetic phases. In the collinear magnetic phase, in which the sublattice magnetic moments are all aligned along the same axis, we observe the conventional spin Hall magnetoresistance. In contrast, in the canted phase, the magnetoresistance changes sign. Using atomistic spin simulations and x-ray absorption experiments, we can understand these observations in terms of the magnetic field and temperature dependent orientation of magnetic moments on different magnetic sublattices. This enables a magnetotransport based investigation of noncollinear magnetic textures. DOI: 10.1103/PhysRevB.94.094401The magnetic properties of ferromagnets are often modeled in terms of a simple macrospin with magnetization vector M. In this picture, one tacitly assumes that all individual atomic magnetic moments μ are aligned in one direction, such that the magnetization is M = nμ with the moment number density n. However, many magnets exhibit a much richer magnetic structure, with canted, spiral, frustrated, or even topological [1,2] phases appearing in addition to collinear magnetic order. Unravelling these experimentally typically requires sophisticated methods, e.g., spin polarized neutron scattering, x-ray magnetic circular dichroism, or Lorentz transmission electron microscopy. A pathway for the electrical detection of magnetic properties is provided by spin torques arising at a magnet/metal interface [3][4][5]. These torques govern fundamental spintronic phenomena such as spin pumping [6][7][8][9][10], spin Seebeck effect [11][12][13], as well as spin Hall magnetoresistance [14][15][16][17][18], and even enable an electrical control of the magnetization in magnetic nanostructures [3][4][5]. However, while the spin torque effect-or more precisely the transfer of spin angular momentum across the magnet/metal interface-has been extensively discussed for a macrospin M [19,20], the action of spin torques on noncollinear magnetic phases is only poorly understood.Here we show that in the ferrimagnet gadolinium iron garnet (Gd 3 Fe 5 O 12 , GdIG), the spin Hall magnetoresistance (SMR) can be used to resolve the orientation of magnetic moments residing on different magnetic sublattices. We thereby prove that the SMR is not just governed by the net moment μ net = μ (viz. the corresponding macrospin magnetization * Present address: Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden, Germany; goennenwein@ wmi.badw.de M net ) aligned along the externally applied magnetic field. This is reflected most conspicuously by the SMR sign inversion observed for canted sublattice moments. The interpretation of our experiments is corroborated by x-ray magnetic circular dichroism (XMCD) measurements, and atomistic spin simulations [13] suggesting that the Fe sublattice moments dominate the SMR response.The SMR originates from spin current transport across the interface between an (insulating) ma...