Search for: All records

Abstract The surface magnetization of Fe₃GeTe₂was examined by low-energy electron microscopy (LEEM) using an off-normal incidence electron beam. We found that the 180° domain walls are of Bloch type. Temperature-dependent LEEM measurements yield a surface magnetization with a surface critical exponentβ1 = 0.79 ± 0.02. This result is consistent with surface magnetism in the 3D semi-infinite Heisenberg (β1 = 0.84 ± 0.01) or Ising (β1 = 0.78 ± 0.02) models, which is distinctly different from the bulk exponent (β= 0.34 ± 0.07). The measurements reveal the power of LEEM with a tilted beam to determine magnetic domain structure in quantum materials without the need for the use of spin-polarized electrons. Single crystal diffraction measurements reveal inversion symmetry-breaking weak peaks and yield space group P-6m2. This Fe site defect-derived loss of inversion symmetry enables the formation of skyrmions in this Fe₃GeTe₂crystal. 

Abstract Alkaline iron (Fe) batteries are attractive due to the high abundance, low cost, and multiple valent states of Fe but show limited columbic efficiency and storage capacity when forming electrochemically inert Fe₃O₄on discharging and parasitic H₂on charging. Herein, sodium silicate is found to promote Fe(OH)₂/FeOOH against Fe(OH)₂/Fe₃O₄conversions. Electrochemical experiments,operandoX‐ray characterization, and atomistic simulations reveal that improved Fe(OH)₂/FeOOH conversion originates from (i) strong interaction between sodium silicate and iron oxide and (ii) silicate‐induced strengthening of hydrogen‐bond networks in electrolytes that inhibits water transport. Furthermore, the silicate additive suppresses hydrogen evolution by impairing energetics of water dissociation and hydroxyl de‐sorption on iron surfaces. This new silicate‐assisted redox chemistry mitigates H₂and Fe₃O₄formation, improving storage capacity (199 mAh g⁻¹in half‐cells) and coulombic efficiency (94 % after 400 full‐cell cycles), paving a path to realizing green battery systems built from earth‐abundant materials.