Charge transfer enhanced magnetic correlations in type-II multiferroic CoTeO.

Magnetic structure of the Co ions in monoclinic CoTeO in the antiferroelectric state at 16 K has been determined by neutron powder together with single-crystal diffractions. The indices of the magnetic reflections that appear at the incommensurate positions were determined by diffractions from a single crystal, which allow to uniquely identify the magnetic modulation vector. There are two crystallographically distinct Co layers.

Room-temperature skyrmion phase in bulk CuOSeO under high pressures.

A skyrmion state in a noncentrosymmetric helimagnet displays topologically protected spin textures with profound technological implications for high-density information storage, ultrafast spintronics, and effective microwave devices. Usually, its equilibrium state in a bulk helimagnet occurs only over a very restricted magnetic field-temperature phase space and often in the low-temperature region near the magnetic transition temperature T We have expanded and enhanced the skyrmion phase region from the small range of 55 to 58.5 K to 5 to 300 K in single-crystalline CuOSeO by pressures up to 42.

Complex magnetic incommensurability and electronic charge transfer through the ferroelectric transition in multiferroic CoTeO.

Polarized and unpolarized neutron diffractions have been carried out to investigate the nature of the magnetic structures and transitions in monoclinic CoTeO. As the temperature is lowered below 26 K long range order develops, which is fully incommensurate (ICM) in all three crystallographic directions. Below 19.

Magnetic ordering and dielectric relaxation in the double perovskite YBaCuFeO.

Using magnetization, dielectric constant, and neutron diffraction measurements on a high quality single crystal of YBaCuFeO (YBCFO), we demonstrate that the crystal shows two antiferromagnetic transitions at [Formula: see text] K and [Formula: see text] K, and displays a giant dielectric constant with a characteristic of the dielectric relaxation at T . It does not show the evidence of the electric polarization for the crystal used for this study. The transition at T corresponds with a paramagnetic to antiferromagnetic transition with a magnetic propagation vector doubling the unit cell along three crystallographic axes.

Spatially Resolved Imaging on Photocarrier Generations and Band Alignments at Perovskite/PbI Heterointerfaces of Perovskite Solar Cells by Light-Modulated Scanning Tunneling Microscopy.

The presence of the PbI passivation layers at perovskite crystal grains has been found to considerably affect the charge carrier transport behaviors and device performance of perovskite solar cells. This work demonstrates the application of a novel light-modulated scanning tunneling microscopy (LM-STM) technique to reveal the interfacial electronic structures at the heterointerfaces between CHNHPbI perovskite crystals and PbI passivation layers of individual perovskite grains under light illumination. Most importantly, this technique enabled the first observation of spatially resolved mapping images of photoinduced interfacial band bending of valence bands and conduction bands and the photogenerated electron and hole carriers at the heterointerfaces of perovskite crystal grains.

Robustness of a Topologically Protected Surface State in a SbTeSe Single Crystal.

A topological insulator (TI) is a quantum material in a new class with attractive properties for physical and technological applications. Here we derive the electronic structure of highly crystalline SbTeSe single crystals studied with angle-resolved photoemission spectra. The result of band mapping reveals that the SbTeSe compound behaves as a p-type semiconductor and has an isolated Dirac cone of a topological surface state, which is highly favored for spintronic and thermoelectric devices because of the dissipation-less surface state and the decreased scattering from bulk bands.

A coordination pi-pi framework exhibits spontaneous magnetization.

A pi-pi scaffolding framework that was assembled as a one-dimensional chain structure comprising alternating Delta- and Lambda-iron(II) chiral building units, [Fe(II)(Delta)Fe(II)(Lambda)(ox)2(phen)2]n, reveals spontaneous magnetization that gives rise to pronounced hysteresis loops below 10 K.