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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 Ferro‐rotational (FR) materials, renowned for their distinctive material functionalities, present challenges in the growth of homo‐FR crystals (i.e., single FR domain). This study explores a cost‐effective approach to growing homo‐FR helimagnetic RbFe(SO₄)₂(RFSO) crystals by lowering the crystal growth temperature below theT_FRthreshold using the high‐pressure hydrothermal method. Through polarized neutron diffraction experiments, it is observed that nearly 86% of RFSO crystals consist of a homo‐FR domain. Notably, RFSO displays remarkable stability in the FR phase, with an exceptionally highT_FRof ≈573 K. Furthermore, RFSO exhibits a chiral helical magnetic structure with switchable ferroelectric polarization below 4 K. Importantly, external electric fields can induce a single magnetic domain state and manipulate its magnetic chirality. The findings suggest that the search for new FR magnets with outstanding material properties should consider magnetic sulfates as promising candidates. 

Exotic perovskites significantly enrich materials for multiferroic and magnetoelectric applications. However, their design and synthesis is a challenge due to the mostly required recipe conditions at extremely high pressure. Herein, we presented the Ca 2−x Mn x MnTaO 6 (0 ≤ x ≤ 1.0) solid solutions stabilized by chemical pressure assisted with intermediate physical pressure up to 7 GPa. The incorporation of Mn 2+ into the A-site neither drives any cationic ordering nor modifies the orthorhombic Pbnm structure, namely written as (Ca 1−x/2 Mn x/2 )(Mn 1/2 Ta 1/2 )O 3 with disordered A and B site cationic arrangements. The increment of x is accompanied by a ferromagnetic to antiferromagnetic transition around x = 0.2, which is attributed to the double-exchange interactions between A-site Mn 2+ and B-site Mn 3+ . Partial charge disproportionation of the B-site Mn 3+ into Mn 2+ and Mn 4+ occurs for x above 0.8 samples as manifested by X-ray spectrum and magnetic behaviors. The coexistence of B-site Mn 3+ (Jahn–Teller distortion ion) and B′-site Ta 5+ (second-order Jahn–Teller distortion ion) could be energetically responsible for the absence of A-site columnar ordering as observed in other quadruple perovskites with half of the A-sites occupied by small transition-metal cations. These exceptional findings indicate that exotic perovskites can be successfully stabilized at chemical and intermediate physical pressure, and the presence of Jahn–Teller distortion cations at the same lattice should be avoided to enable cationic ordering.