Heavy fermion compounds exhibiting a ferromagnetic quantum critical point have attracted considerable interest. Common to two known cases, i.e., CeRh_{6}Ge_{4} and YbNi_{4}P_{2}, is that the 4f moments reside along chains with a large interchain distance, exhibiting strong magnetic anisotropy that was proposed to be vital for the ferromagnetic quantum criticality. Here, we report an angle-resolved photoemission study on CeRh_{6}Ge_{4} in which we observe sharp momentum-dependent 4f bands and clear bending of the conduction bands near the Fermi level, indicating considerable hybridization between conduction and 4f electrons. The extracted hybridization strength is anisotropic in momentum space and is obviously stronger along the Ce chain direction.The hybridized 4f bands persist up to high temperatures, and the evolution of their intensity shows clear band dependence. Our results provide spectroscopic evidence for anisotropic hybridization between conduction and 4f electrons in CeRh_{6}Ge_{4}, which could be important for understanding the electronic origin of the ferromagnetic quantum criticality.

The impact of nonmagnetic and magnetic impurities on topological insulators is a central focus concerning their fundamental physics and possible spintronics and quantum computing applications. Combining scanning tunneling spectroscopy with transport measurements, we investigate, both locally and globally, the effect of nonmagnetic and magnetic substituents in SmB₆, a predicted topological Kondo insulator. Around the so-introduced substitutents and in accord with theoretical predictions, the surface states are locally suppressed with different length scales depending on the substituent's magnetic properties. For sufficiently high substituent concentrations, these states are globally destroyed. Similarly, using a magnetic tip in tunneling spectroscopy also resulted in largely suppressed surface states. Hence, a destruction of the surface states is always observed close to atoms with substantial magnetic moment. This points to the topological nature of the surface states in SmB₆ and illustrates how magnetic impurities destroy the surface states from microscopic to macroscopic length scales.

Most iron-based superconductors exhibit stripe-type magnetism, characterized by the ordering vector Q=(12,12). In contrast, Fe1+yTe, the parent compound of the Fe1+yTe1-xSex superconductors, exhibits double-stripe magnetic order associated with the ordering vector Q=(12,0). Here, we use elastic neutron scattering to investigate heavily Cu-substituted (Fe1-xCux)1+yTe compounds and reveal that (1) for x0.4, short-range magnetic order emerges around the stripe-type vector at Q=(12±δ,12±δ,12) with δ≈0.05; (2) the short-range magnetic order is associated with a superstructure modulation at Q=(13,13,12), with the magnetic correlation length shorter than that for the superstructure; and (3) for x0.55, we observe an additional intergrown phase with higher Cu content, characterized by a superstructure modulation vector Q=(13,13,0) and magnetic peaks at Q=(23,13,12)/(13,23,12). The positions of superstructure peaks suggest that relative to the tetragonal unit cell of Fe1+yTe, heavy Cu substitution leads to Fe-Cu orderings that expand the unit cell by 2×32 times in the ab plane, corroborated by first-principles calculations that suggest the formation of spin chains and spin ladders. Our findings show that stripe-type magnetism is common in magnetically diluted iron pnictides and chalcogenides, despite the varying associated atomic orderings.