Spontaneous Topological Magnetic Transitions in NdCo₅ Rare‐Earth Magnets

Abstract

Particle‐like magnetic textures with nanometric sizes, such as skyrmions, are potentially suitable for designing high‐efficiency information bits in future spintronics devices. In general, the Dzyaloshinskii–Moriya interactions and dipolar interactions are the dominant factors for generating nonlinear spin configurations. However, to stabilize the topological skyrmions, an external magnetic field is usually required. In this study, the spontaneous emergence of skyrmions is directly observed, together with the unique successive topological domain evolution during the spin reorientation transition in a neodymium–cobalt (NdCo5) rare‐earth magnet. On decreasing the temperature, nanometric skyrmion lattices evolve into enclosed in‐plane domains (EIPDs) similar to mini bar‐magnets with size below 120 nm. The internal magnetization rotates with magnetic anisotropy, demonstrating the ability to manipulate the mini bar‐magnets. The nanoscale EIPD lattices remain robust over the wide temperature range of 241–167 K, indicating the possibility of high‐density in‐plane magnetic information storage. The generation of spontaneous magnetic skyrmions and the successive domain transformation in the traditional NdCo5 rare‐earth magnet may prompt application exploration for topological magnetic spin textures with novel physical mechanisms in versatile magnets.

Controllable Topological Magnetic Transformations in the Thickness-Tunable van der Waals Ferromagnet Fe5GeTe2

“…The Curie temperature ( T c ) of FGT in this work was determined to be about 270 K through the magnetization derivative as a function of temperature (see Figure S1 in the Supporting Information). Moreover, it has been found that the magnetocrystalline anisotropy changes with temperature in many uniaxial magnets, such as Fe 3 Sn 2 and NdCo 5 and even the Fe n GeTe 2 systems that have been widely investigated recently, which could induce a spin reorientation transition (SRT) that promises the emergence of noncollinear magnetic textures. Hence, to reveal the magnetic properties of FGT further, M–H curves were measured at different temperatures with a magnetic field parallel to the c axis and ab plane (see Figure c).…”

Spontaneous Biskyrmion Lattice in a Centrosymmetric Rhombohedral Rare-Earth Magnet with Easy-Plane Anisotropy

“…More importantly, spontaneous biskyrmions could exist at a higher temperature (>300 K) including room temperature in the heating process. Although the domain evolution between biskyrmions and EIPDs looks similar in Nd 2 Co 17 and NdCo 5 , the relatively strong easy-plane anisotropy in the soft magnet Nd 2 Co 17 indicates significantly different biskyrmion origination in contrast to those in NdCo 5 determined by the uniaxial anisotropy near T c …”

“…The existence of skyrmions at room temperature and zero field, i.e., spontaneous skyrmions at room temperature, is highly anticipated for spintronic applications. However, despite the theoretically proposed spontaneous ground state, − the experimental discovery is very limited , especially at room temperature and in materials with easy-plane magnetic anisotropy.…”

Magnetic Skyrmions with Unconventional Helicity Polarization in a Van Der Waals Ferromagnet

“…[56] Furthermore, the topology of the "Yin-Yang" symbol in the green box remains controversial. [57] Some research proposed that it was a biskyrmion, [58][59][60] whereas recent reports claimed that it was a modified trivial bubble. [21,61] Further detailed analysis of this spin texture is beyond the scope of this study.…”