Search for: All records

We report the two-dimensional (2D) bimetallic selenophosphate, LiGaP2Se6, prepared through direct combination reactions and P2Se5 flux methods. The material is a member of the broad class of van der Waals 2D materials of the type M2P2Q6 (M = metals). The structure was determined using single-crystal X-ray diffraction and refined in the chiral space group P3̅1c, with lattice parameters a = b = 6.2993(9) Å, c = 13.308(3) Å, α = β = 90°, γ = 120°. Differential thermal analysis indicated a congruent melting point at ∼458 °C. Optoelectronic properties were assessed using ultraviolet–visible (UV–vis) spectroscopy, showing a band gap of 2.01 eV, and photoemission yield spectroscopy in air (PYSA), which determined a work function of 5.44 eV. Notably, stability studies on LiGaP2Se6 revealed remarkable resilience despite its Li content, showing no structural changes after 2 weeks in ambient air or after soaking in a water/ethanol bath. 

Persistent spin texture (PST) describes a unique spin‐momentum locking in momentum space that maintains a uniform spin orientation through portions of the Brillouin zone (BZ), enabling exceptionally long spin lifetimes, which are essential for applications in spintronics. However, materials exhibiting large BZ regions of high‐quality PST, characterized by minimal spin deviation and long spin lifetimes, remain scarce. Here, a universal model is introduced to capture the formation of superior PST regions arising from the interplay of spin–orbit fields at differentkpoints. Within this framework, high‐quality PSTs are identified in several systems belonging to various point groups. Notably, the nonpolar‐chiral compound Na₂Sn₂O₃exhibits a 0.02 Å⁻²high‐quality PST region, which can be reversed by the switching of geometric chirality, while AgClO₄(D_2dsymmetry) exhibits a 0.016 Å⁻²PST region. Significantly, Na₂Sn₂O₃and AgClO₄are predicted to host persistent spin helices with spin lifetimes of 0.5–7.4 and 0.9–2.5 ns, respectively, among the longest reported for PST materials. In addition, both chemical substitution and the application of pressure are demonstrated as effective routes for engineering high‐quality PST. Our findings not only establish a universal principle for high‐quality PST, but also provide promising materials across various point groups for the next‐generation spintronic devices. 

A revised crystal structure of La(OH)2Cl is reported. This material is found to crystallize in space group P21/m and is isostructural to a series of Ln(OH)2Cl (Ln = Ce – Lu excluding Pm). The Ln(OH)2Cl series has been thoroughly studied, serving as analogues to proposed actinide structures for used nuclear fuel storage. The P21/m space group has been reported for each isostructural variant in this series. La(OH)2Cl is described in the context of the structural trends identified with this series. A lanthanum variant was previously reported, however, with symmetry corresponding to the space group P2/m. The data collected herein is compared to the previously published La(OH)2Cl in the space group P2/m. Here, we report an updated hydrothermal synthesis and revised crystallographic structure for La(OH)2Cl in P21/m. The reflection conditions of the collected X‐ray diffraction data, the bond valence sums of both structures, and density functional theory calculations are examined to justify the revised space group assignments.