A novel class of one-dimensional Ta4TMTe4 (TM = Cr, Fe, Co and Ni) compounds with strain-switched magnetic states

ANi5Bi5.6+δ (A = K, Rb, and Cs): Quasi-One-Dimensional Metals Featuring [Ni5Bi5.6+δ]- Double-Walled Column with Strong Diamagnetism

A new series of compounds, ANi₅Bi_5.6+δ (where A = K, Rb, and Cs) are discovered with a quasi-one-dimensional (Q1D) [Ni₅Bi_5.6+δ]^- double-walled column and a coaxial inner one-dimensional Bi atomic chain. The columns are linked to each other by intercolumn Bi-Bi bonds and separated by an A⁺ cation. Typical metallic behaviors with strong correlation of itinerant electrons and the Sommerfeld coefficient enhanced with the increasing cationic radius were experimentally observed and supported by first-principles calculations. Compared to AMn₆Bi₅ (where A = K, Rb, and Cs), the enhanced intercolumn distances and the substitution of Ni for Mn give rise to strong diamagnetic susceptibilities in ANi₅Bi_5.6+δ. First-principles calculations reveal possible uncharged Ni atoms with even number of electrons in ANi₅Bi_5.6+δ, which may explain the emergence of diamagnetism. ANi₅Bi_5.6+δ, as Q1D diamagnetic metals with strong electron correlation, provide a unique platform to understand exotic magnetism and explore novel quantum effects.

Magneto-electronics, transport properties, and tuning effects of arsenene armchair nanotubes doped with transition metal atoms

Recently, the arsenic monolayer has been successfully fabricated by micromechanical stripping. However, it is a non-magnetic semiconductor, including its derivatives. Here, we theoretically explore how to induce magnetism for arsenene armchair nanotubes (AsANTs) with a low-concentration TM (TM = Co, Y, Rh, Ni, Mo, Ru) atom doping, especially focusing on their structural stability, magneto-electronic property, carrier mobility, and strain effects. The high stability of these doped tubes are confirmed by the calculated binding energy and formation energy, as well as Forcite annealing molecular dynamics simulations. The AsANT can act as bandgap narrowed non-magnetic semiconductors or highly spin-polarized magnetic semiconductors (half-semiconductor or bipolar magnetic semiconductor) depending on TM types, suggesting different promising applications such as developing infrared photodetectors with broadband detectionin or spintronic devices. The magnetic thermal stability beyond room temperature is predicted for doped tubes. Furthermore, the carrier mobility of AsANTs can be tuned into a wide region by TM doping, but it is enhanced in most cases. The carrier and spin polarity of mobility can also be clearly observed. Particularly, the applied strain can induce a rich magnetic phase transition among a half-semiconductor, half-metal, bipolar magnetic semiconductor and nonmagnetic state. Furthermore, the presented stepwise change of total magnetic moment between high magnetized and nonmagnetic states is highly desirable for engineering a mechanical switch which can reversibly work between magnetism and demagnetism to control spin-polarized transport by applying strain.