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Abstract We report high-pressure x-ray diffraction and electrical resistance measurements on Sr(Co_0.88Ni_0.12)₂P₂, an itinerant antiferromagnet with the highest Néel temperature (T_N= 36 K) among Sr(Co_1−xNi_x)₂P₂series. Room-temperature diffraction data reveal a pressure-induced transition from an uncollapsed tetragonal (ucT) to a collapsed tetragonal (cT) structure, beginning near 8.4 GPa and completing before 12.4 GPa. This transition is characterized by an expansion of the in-plane a-lattice parameter and a contraction in the c-lattice parameter, resulting in a reduction of the axial ratio c/a. Resistance measurements show a low-pressure anomaly near 38 K, consistent with the reported antiferromagnetic transition. As the room temperature value of the applied pressure exceeds 8 GPa, signs of a partial cT transition appear on cooling with the full cT transition occurring for pressures exceeding 10 GPa. Associated with the cT phase is a much higher temperature ferromagnetic transition with Curie temperature reaching ∼ 190 K before slowly decreasing for higher applied pressures. These results demonstrate strong coupling between the lattice collapse and magnetic behavior in Sr(Co_0.88Ni_0.12)₂P₂. 

ReMo binary alloy films with a maximum Mo content of 25 at. % are successfully electrodeposited using high concentration acetate solutions in the presence of citric acid. The electrochemical behavior of the ReMo alloy is studied using cyclic voltammetry and anodic stripping methods. Different techniques, including electron microscopy, x-ray diffraction, and four-point probe resistance measurements at cryogenic temperature, are used to characterize the surface morphology, crystal structure, and superconducting critical temperature of alloys, respectively. While all films exhibit a crystalline hcp phase after 700 °C annealing, the film with the highest 25 at. % Mo content shows a second crystalline cubic phase. Mo doping preserves the enhanced superconducting transition temperature (Tc) in electrodeposited amorphous Re films and improves the stability of Tc against thermal annealing at a temperature of 200 °C. This is the first successful demonstration to use a dopant to stabilize the enhanced Tc of electrodeposited films, enabling the fabrication and operation of superconducting connectors above the intrinsic Tc of the materials. 

This study systematically investigates the magnetic properties of the layered ferromagnet MnPt5As under pressure through a combination of experimental measurements and theoretical simulations. MnPt5As exhibits a ferromagnetic transition at approximately 301 K. Neutron diffraction measurements under applied pressures up to ∼4.9 GPa were performed over a temperature range from 320 to 100 K to probe its magnetic behavior. The results confirm that the Mn atoms maintain a ferromagnetic order under applied pressures, consistent with the ambient-pressure findings. However, magnetic anisotropy is notably suppressed. To further elucidate the compressibility of magnetic anisotropy in MnPt5As, x-ray diffraction under pressure was conducted. The results reveal that the c-axis undergoes a greater and more rapid compression compared to the ab-plane, which may contribute to the observed suppression of Mn ferromagnetic ordering along the c-axis. Additionally, theoretical calculations indicate that magnetic ordering exhibits a similar pressure-induced trend under applied pressure, supporting the experimental observations. These findings offer insights into the pressure-dependent magnetic properties and anisotropy of MnPt5As, with potential implications for strain engineering in Mn-based magnetic devices. 

High-entropy alloys (HEAs) are a class of multi-element materials that exhibit unique structural and functional properties. This study reports on the synthesis and characterization of a superconducting HEA, (NbTa)0.55(HfTiZr)0.45 fabricated using the vacuum arc melting technique. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were employed to analyze the material's morphology and composition. X-ray diffraction analysis revealed a single-phase body-centered cubic (BCC) structure with a measured nanoindentation hardness of 6.4 GPa and Young's modulus of 132 GPa. This HEA superconductor was investigated by x-ray diffraction at Beamline 13BM-C, Advanced Photon Source, and the BCC phase was stable to the highest pressure of 50 GPa. Superconductivity was characterized by four-probe resistivity measurements in a quantum design physical property measurement system, yielding a superconducting transition temperature (Tc) of 7.2 K at ambient pressure and reaching a maximum of 10.1 K at the highest applied pressure of 23.6 GPa. The combination of high structural stability enhanced superconducting performance under pressure and superior mechanical properties highlights (NbTa)0.55(HfTiZr)0.45 as a promising superconductor under extreme environments. 

We report on a novel TaNbZrHfTi-based high entropy alloy (HEA) which demonstrates distinctive dual-phase superconductivity. The HEA was synthesized under high pressures and high temperatures starting from a ball milled mixture of elemental metals in a large-volume Paris–Edinburgh cell with P ≈ 6 GPa and T = 2300 K. The synthesized HEA is a phase mixture of BCC (NbTa)0.45(ZrHfTi)0.55 with Tc1 = 6 K and FCC (NbTa)0.04(ZrHfTi)0.96 with Tc2 = 3.75 K. The measured magnetic field parameters for the HEA are lower critical field, Hc1(0) = 31 mT, and a relatively high upper critical field, Hc2(0) = 4.92 T. This dual-phase system is further characterized by the presence of a second magnetization peak, or the fishtail effect, observed in the virgin magnetization curves. This phenomenon, which does not distort the field-dependent magnetization hysteresis loops, suggests intricate pinning mechanisms that could be potentially tuned for optimized performance. The manifestation of these unique features in HEA superconductivity reinforces phase-dependent superconductivity and opens new avenues in the exploration of novel superconducting materials. 

Abstract Dirac materials offer exciting opportunities to explore low-energy carrier dynamics and novel physical phenomena, especially their interaction with magnetism. In this context, this work focuses on studies of pressure control on the magnetic state of EuMnBi₂, a representative magnetic Dirac semimetal, through time-domain synchrotron M¨ossbauer spectroscopy in¹⁵¹Eu. Contrary to the previous report that the antiferromagnetic order is suppressed by pressure above 4 GPa, we have observed robust magnetic order up to 33.1 GPa. Synchrotron-based x-ray diffraction experiment on a pure EuMnBi₂sample shows that the tetragonal crystal lattice remains stable up to 31.7 GPa.