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Although the frustrated (zigzag) spin chain is the Drosophila of frustrated magnetism, our understanding of a pair of coupled zigzag chains (frustrated spin ladder) in a magnetic field is still lacking. We address this problem through nuclear magnetic resonance (NMR) experiments on BiCu 2 PO 6 in magnetic fields up to 45 T, revealing a field-induced spiral magnetic structure. Conjointly, we present advanced numerical calculations showing that even a moderate rung coupling dramatically simplifies the phase diagram below half-saturation magnetization by stabilizing a field-induced chiral phase. Surprisingly for a one-dimensional model, this phase and its response to Dzyaloshinskii-Moriya (DM) interactions adhere to classical expectations. While explaining the behavior at the highest accessible magnetic fields, our results imply a different origin for the solitonic phases occurring at lower fields in BiCu 2 PO 6 . An exciting possibility is that the known, DM-mediated coupling between chirality and crystal lattice may give rise to a new kind of spin-Peierls instability.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Employing X‐ray magnetic circular dichroism (XMCD), angle‐resolved photoemission spectroscopy (ARPES), and momentum‐resolved density fluctuation (MRDF) theory, the magnetic and electronic properties of ultrathin NdNiO3 (NNO) film in proximity to ferromagnetic (FM) La0.67Sr0.33MnO3 (LSMO) layer are investigated. The experimental data shows the direct magnetic coupling between the nickelate film and the manganite layer which causes an unusual ferromagnetic (FM) phase in NNO. Moreover, it is shown the metal–insulator transition in the NNO layer, identified by an abrupt suppression of ARPES spectral weight near the Fermi level (EF), is absent. This observation suggests that the insulating AFM ground state is quenched in proximity to the FM layer. Combining the experimental data (XMCD and AREPS) with the momentum‐resolved density fluctuation calculation (MRDF) reveals a direct link between the MIT and the magnetic orders in NNO systems. This work demonstrates that the proximity layer order can be broadly used to modify physical properties and enrich the phase diagram of RENiO3 (RE = rare‐earth element). The ferromagnetic order in NdNiO3 (NNO) film is induced by the stray field from the La0.67Sr0.33MnO3 (LSMO) layer in proximity. Consequently, the magnetic coupling between the NNO film and the LSMO layer melts the metal–insulator transition in the NNO layer. Thus, this study illuminates the intimate connection between magnetic order and electronic properties in RENO.

Many superconducting materials allow the penetration of magnetic fields in a mixed state in which the superfluid is threaded by a regular lattice of Abrikosov vortices, each carrying one quantum of magnetic flux. The phenomenological Ginzburg-Landau theory, based on the concept of characteristic length scales, has generally provided a good description of the Abrikosov vortex lattice state. We conducted neutron-scattering measurements of the vortex lattice form factor in the heavy-fermion superconductor cerium-cobalt-indium (CeCoIn₅) and found that this form factor increases with increasing field--opposite to the expectations within the Abrikosov-Ginzburg-Landau paradigm. We propose that the anomalous field dependence of the form factor arises from Pauli paramagnetic effects around the vortex cores and from the proximity of the superconducting state to a quantum critical point.

Superconductivity: Putting the pressure on iron-based superconductors Experiments show how iron-based superconductors synthesized under high pressure differ from those grown under ambient conditions. Iron-based superconductors are an exciting family of materials that exhibit unconventional superconductivity as well as a range of other exotic phases due to a complex interplay between magnetism and superconductivity. Oxypnictides are particularly puzzling members of this family as seemingly similar compounds can exhibit strikingly different electronic properties. By growing and measuring a range of oxypnictide compounds grown under different high-pressure, high-temperature conditions a team of researchers from Switzerland, led by Toni Shiroka from ETH Zürich, show that a close interplay between the magnetism and superconductivity is meditated by spin fluctuations. Furthermore, they show that the superconducting order parameter evolves in a way that is completely opposite to ambient-grown samples.

The dynamics of individual particles such as atoms, electrons, and their spins changes in a dramatic manner when these particles form a periodic solid. Improvements in neutron scattering techniques allow precise measurement of dynamics in magnetically ordered condensed matter materials.

Similar to chemical doping, pressure produces and stabilizes new phases of known materials, whose properties may differ greatly from those of their standard counterparts. Here, by considering a series of LaFeAs 1− x P x O iron-pnictides synthesized under high-pressure high-temperature conditions, we investigate the simultaneous effects of pressure and isoelectronic doping in the 1111 family. Results of numerous macroscopic and microscopic technique measurements unambiguously show a radically different phase diagram for the pressure-grown materials, characterized by the lack of magnetic order and the persistence of superconductivity across the whole 0.3 ≤  x  ≤ 0.7 doping range. This unexpected scenario is accompanied by a branching in the electronic properties across x  = 0.5, involving both the normal and superconducting phases. Most notably, the superconducting order parameter evolves from nodal (for x  < 0.5) to nodeless (for x  ≥ 0.5), in clear contrast to other 1111 and 122 iron-based materials grown under ambient-pressure conditions. Superconductivity: Putting the pressure on iron-based superconductors Experiments show how iron-based superconductors synthesized under high pressure differ from those grown under ambient conditions. Iron-based superconductors are an exciting family of materials that exhibit unconventional superconductivity as well as a range of other exotic phases due to a complex interplay between magnetism and superconductivity. Oxypnictides are particularly puzzling members of this family as seemingly similar compounds can exhibit strikingly different electronic properties. By growing and measuring a range of oxypnictide compounds grown under different high-pressure, high-temperature conditions a team of researchers from Switzerland, led by Toni Shiroka from ETH Zürich, show that a close interplay between the magnetism and superconductivity is meditated by spin fluctuations. Furthermore, they show that the superconducting order parameter evolves in a way that is completely opposite to ambient-grown samples.

Employing X‐ray magnetic circular dichroism (XMCD), angle‐resolved photoemission spectroscopy (ARPES), and momentum‐resolved density fluctuation (MRDF) theory, the magnetic and electronic properties of ultrathin NdNiO 3 (NNO) film in proximity to ferromagnetic (FM) La 0.67 Sr 0.33 MnO 3 (LSMO) layer are investigated. The experimental data shows the direct magnetic coupling between the nickelate film and the manganite layer which causes an unusual ferromagnetic (FM) phase in NNO. Moreover, it is shown the metal–insulator transition in the NNO layer, identified by an abrupt suppression of ARPES spectral weight near the Fermi level ( E F ), is absent. This observation suggests that the insulating AFM ground state is quenched in proximity to the FM layer. Combining the experimental data (XMCD and AREPS) with the momentum‐resolved density fluctuation calculation (MRDF) reveals a direct link between the MIT and the magnetic orders in NNO systems. This work demonstrates that the proximity layer order can be broadly used to modify physical properties and enrich the phase diagram of RENiO 3 (RE = rare‐earth element).