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Rich nontrivial topological phases rooted in the interplay between magnetism and topology in the layered antiferromagnet EuCd2As2 have captured vast attention, especially the ideal Weyl semimetal state realized in the spin‐polarized ferromagnetic (FM) structure driven by a moderate external magnetic field. In this work, combining magnetization, magneto‐transport, and structure measurements under high pressure and first principles calculations, this study finds that the pressure can drive the in‐plane antiferromagnetic structure of EuCd2As2 across an intermediate in‐plane FM structure then into the out‐of‐plane FM structure. This study also finds butterfly‐shaped MR and anomalous Hall effect under large pressure, which may support the pressure‐driven FM state. High‐pressure angle‐dispersive X‐ray diffraction and X‐ray absorption near‐edge spectroscopy measurements exclude structure transition and/or change of Eu2+ valence state as sources for the magnetic phase transitions. Alternatively, apparently reduced axial ratio (c/a) and compressed Eu‐layer space distance should play important roles. Interestingly, the calculations unveil that the out‐of‐plane FM structure hosts only one pair of Weyl nodes around the Fermi level, suggesting that pressure can be an alternative way to realize the ideal Weyl semimetal state in EuCd2As2 and will be useful for exploring exotic topological properties in such layered magnetic topological phase with strongly competing magnetic exchanges. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) nanowires with two different dimensions (i.e., <100 nm and ∼200 nm in diameter) were synthesized and studied under high pressure up to 37 GPa by Raman spectroscopy and synchrotron X-ray diffraction. Direct anatase to baddeleyite phase transitions were observed in both samples upon compression, but with different onset pressures. The observed phase transitions are in contrast to bulk TiO2, where the anatase phase transforms to α-PbO2 phase and then the baddeleyite phase. Compressibility of the anatase and baddeleyite phases was found different than both nanocrystals and the corresponding bulk materials. Our comparative study demonstrated not only that the morphology of TiO2 nanowire substantially influences the high pressure behaviors, but dimensions play a determining role in terms of transformation pressures, phase stability regions, and compressibility. [ABSTRACT FROM AUTHOR]

Metallic glasses (MGs) have unusual structural characteristics and resulting unique properties, but effectively modulating their structure is difficult. The recently achieved two-way structural tuning (ordering-disordering) between distinct states in MGs offers an opportunity to overcome this challenge. However, pressures up to tens of GPa were required for the process, which limits sample sizes at the micrometer scale and challenges further comprehensive research. Here, by introducing concurrent shear straining with compressive force using high-pressure torsion, the pressure to trigger the disordering transition is significantly reduced to a few GPa. This enables the acquisition of millimeter-sized samples for comprehensive study, including synchrotron x-ray diffraction and small angle x-ray scatting, nanoindentation, electrical resistivity, and differential scanning calorimetry. It is evidenced that the two-way tuning of MG can be achieved both structurally and thermodynamically, which could help deepen our understanding of the mechanism behind the two-way tuning and promote exploration of distinct MGs. [Display omitted] [ABSTRACT FROM AUTHOR]