Probing magnetic ordering in air stable iron-rich van der Waals minerals

In the rapidly expanding field of two-dimensional materials, magnetic monolayers show great promise for the future applications in nanoelectronics, data storage, and sensing. The research in intrinsically magnetic two-dimensional materials mainly focuses on synthetic iodide and telluride based compounds, which inherently suffer from the lack of ambient stability. So far, naturally occurring layered magnetic materials have been vastly overlooked. These minerals offer a unique opportunity to explore air-stable complex layered systems with high concentration of local moment bearing ions. We demonstrate magnetic ordering in iron-rich two-dimensional phyllosilicates, focusing on mineral species of minnesotaite, annite, and biotite. These are naturally occurring van der Waals magnetic materials which integrate local moment baring ions of iron via magnesium/aluminium substitution in their octahedral sites. Due to self-inherent capping by silicate/aluminate tetrahedral groups, ultra-thin layers are air-stable. Chemical characterization, quantitative elemental analysis, and iron oxidation states were determined via Raman spectroscopy, wavelength disperse X-ray spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Superconducting quantum interference device magnetometry measurements were performed to examine the magnetic ordering. These layered materials exhibit paramagnetic or superparamagnetic characteristics at room temperature. At low temperature ferrimagnetic or antiferromagnetic ordering occurs, with the critical ordering temperature of 38.7 K for minnesotaite, 36.1 K for annite, and 4.9 K for biotite. In-field magnetic force microscopy on iron bearing phyllosilicates confirmed the paramagnetic response at room temperature, present down to monolayers.Comment: 19 pages, 6 figure

Ein Vorkommen von marinem Perm im nördlichen Ala Dagh. (Kilikischer Taurus, Türkei)

Donated by Klaus KreiserReprinted from in : Hölder-Pichler-Tempsky Wien Leipzig Akad d. Wiss, Wien Leipzig, 1939

Beiträge zur geologie des kilikischen Taurus im gebiete des Ala Dagh

Donated by Klaus KreiserReprinted from in : Hölder-Pichler-Tempsky Wien Leipzig Akad d. Wiss, Wien Leipzig, 1939

Berg- und hüttenmännisches Jahrbuch.

Mode of access: Internet.Issued by the Montanistische Hochschule in Leoben (with the Montanistische Hochschule in Pr̆ibram, 1855-1912, and with the Bergakademie zu Schemnitz, 1858-1904).Continuation of Jahrbuch der K. K. Montanlehranstalt zu Leoben. Cf. L C 1942

Fracture statistics of brittle materials: Weibull or normal distribution

The fit of fracture strength data of brittle materials (Si3N4, SiC, and ZnO) to the Weibull and normal distributions is compared in terms of the Akaike information criterion. For Si3N4, the Weibull distribution fits the data better than the normal distribution, but for ZnO the result is just the opposite. In the case of SiC, the difference is not large enough to make a clear distinction between the two distributions. There is not sufficient evidence to show that the Weibull distribution is always preferred to other distributions, and the uncritical use of the Weibull distribution for strength data is questioned