In the search for multiferroic materials magnetic compounds with a strongly elongated unit-cell (large axial ratio c/a) have been scrutinized intensely. However, none was hitherto proven to have a switchable polarization, an essential feature of ferroelectrics. Here, we provide evidence for the epitaxial stabilization of a monoclinic phase of BiFeO3 with a giant axial ratio (c/a=1.23) that is both ferroelectric and magnetic at room temperature. Surprisingly, and in contrast with previous theoretical predictions, the polarization does not increase dramatically with c/a. We discuss our results in terms of the competition between polar and antiferrodistortive instabilities and give perspectives for engineering multiferroic phases.

We report element specific structural and magnetic investigations on Zn(1-x)Co(x)O epitaxial films using synchrotron radiation. Co dopants exclusively occupy Zn sites as revealed by x-ray linear dichroism having an unprecedented degree of structural perfection. Comparative magnetic field dependent measurements by x-ray magnetic circular dichroism and conventional magnetometry consistently show purely paramagnetic behavior for isolated Co dopant atoms with a magnetic moment of 4.8 (mu B). However, the total magnetization is reduced by approximately 30%, demonstrating that Co-O-Co pairs are antiferromagnetically coupled. We find no sign of intrinsic ferromagnetic interactions for isolated or paired Co dopant atoms in Co:ZnO films.

The magnetic moments in Ni/Pt multilayers are thoroughly studied by combining experimental and ab initio theoretical techniques. SQUID magnetometry probes the samples' magnetizations. X-ray magnetic circular dichroism separates the contribution of Ni and Pt and provides a layer-resolved magnetic moment profile for the whole system. The results are compared to band-structure calculations. Induced Pt magnetic moments localized mostly at the interface are revealed. No magnetically "dead" Ni layers are found. The magnetization per Ni volume is slightly enhanced compared to bulk NiPt alloys.

Magneto-chiral dichroism (MχD) is a non-reciprocal, i. e. directional, effect observed in magnetised chiral systems featuring an unbalanced absorption of unpolarised light depending on the direction of the magnetisation. Despite the fundamental interest in a phenomenon breaking both parity and time reversal symmetries, MχD is one of the least investigated aspects of light-matter interaction because of the weakness of the effect in most reported experiments. Here we have exploited the element selectivity of hard X-ray radiation to investigate the magneto-chiral properties of enentiopure crsytals of two isostructural molecular helicoidal chains comprising Cobalt(II) and Manganese (II) ions, respectively. A strong magneto-chiral dichroism, with Kuhn asymmetry of the order of a few percent, has been observed in the Cobalt chain system, while it is practically absent for the Manganese derivative. The spectral features of the XMχD signal differ significantly from the natural and magnetic dichroic contributions and have been here rationalized using the simple multipolar expansion of matter-radiation interaction.

Using X-ray magnetic circular dichroism (XMCD) measurements, we explore the possible existence of induced magnetic moments in thin Pt films deposited onto the ferrimagnetic insulator yttrium iron garnet (Y3Fe5O12). Such a magnetic proximity effect is well established for Pt/ferromagnetic metal heterostructures. Indeed, we observe a clear XMCD signal at the Pt L3 edge in Pt/Fe bilayers, while no such signal can be discerned in XMCD traces of Pt/Y3Fe5O12 bilayers. Integrating the XMCD signals allows to estimate an upper limit for the induced Pt magnetic polarization in Pt/Y3Fe5O12 bilayers.PACS numbers: 78.70. Dm, 75.70.Cn, 75.50.Dd, 81.15.Fg Pure spin currents are a fascinating manifestation of spin physics in the solid state.1-6 Experimentally, the generation or detection of spin currents is often based on the interconversion of spin and charge currents, taking advantage of the spin Hall or the inverse spin Hall effect, respectively. 1,3,4,6 This makes normal metal/ferromagnetic metal (NM/FMM) or normal metal/ferromagnetic insulator (NM/FMI) heterostructures very attractive.7 In so-called spin pumping 4,5,8,9 or spin Seebeck experiments, 6,10-13 the magnetization in the ferromagnetic constituent is driven out of thermal equilibrium, and the ensuing spin current into the normal metal (NM) layer is detected via the corresponding inverse spin Hall electrical current in these heterostructures. Hereby, the paramagnetic NM layer is commonly considered as 'non-magnetic' in the sense that its spin polarization is negligibly small, such that magneto-resistive or magneto-thermo-galvanic effects in the NM layer can be safely ignored.6,14 This assumption appears reasonable for NM/FMM bilayers, in which the unavoidable magneto-thermo-galvanic response of the FMM layer dominates. In contrast, for the case of NM/FMI structures, the absence of an induced spin polarization in the NM layer and thus the complete absence of magnetothermo-galvanic effects in the FMI such as the anomalous Nernst effect are considered as an advantage and even exploited for the interpretation.6,14 Very recently, magnetic proximity effects in NM/FMI structures were inferred from electrical and thermal magnetotransport measurements.15 Thus, a careful investigation of a possible finite induced magnetic polarization in the NM layer in NM/FMI heterostructures is essential for the correct interpretation of spin current related phenomena. In NM/FMM heterostructures and alloys using 3d and 5d elements, the presence of an induced spin polarization in the NM layer in proximity to the interface has been observed by X-ray magnetic circular dichroism (XMCD) experiments.16-20 To our knowledge, no such investigations have been performed in NM/FMI heterostructures.