Chiral Helimagnetism and One‐Dimensional Magnetic Solitons in a Cr‐Intercalated Transition Metal Dichalcogenide

Abstract

Chiral magnets endowed with topological spin textures are expected to have promising applications in next‐generation magnetic memories. In contrast to the well‐studied 2D or 3D magnetic skyrmions, the authors report the discovery of 1D nontrivial magnetic solitons in a transition metal dichalcogenide 2H‐TaS2 via precise intercalation of Cr elements. In the synthetic Cr1/3TaS2 (CTS) single crystal, the coupling of the strong spin–orbit interaction from TaS2 and the chiral arrangement of the magnetic Cr ions evoke a robust Dzyaloshinskii–Moriya interaction. A magnetic helix having a short spatial period of ≈25 nm is observed in CTS via Lorentz transmission electron microscopy. In a magnetic field perpendicular to the helical axis, the helical spin structure transforms into a chiral soliton lattice (CSL) with the spin structure evolution being consistent with the chiral sine‐Gordon theory, which opens promising perspectives for the application of CSL to fast‐speed nonvolatile magnetic memories. This work introduces a new paradigm to soliton physics and provides an effective strategy for seeking novel 2D magnets.

Structure and Magnetism of Iron- and Chromium-Intercalated Niobium and Tantalum Disulfides

“…As a result, the period of the chiral helimagnetic ground state, which is proportional to the ratio between the FM exchange interaction and the DM interaction, 86 decreases from Cr 1/3 NbS 2 to Cr 1/3 TaS 2 . 18,19 As we shall discuss below, other magnetic properties, including T C and critical field (above which the material enters a forced ferromagnetic state), are consistent with stronger magnetocrystalline anisotropy in Cr 1/3 TaS 2 .…”

“…In noncentrosymmetric systems, such as T 1/3 M S 2 with a √ 3 × √ 3 superlattice structure, DM interactions favor canting between neighboring spins and can result in chiral spin textures. 52 For instance, the Cr 1/3 M S 2 materials exhibit chiral helimagnetic ground states, [17][18][19]26 and spin canting has been proposed in Fe 1/3 NbS 2 . 24 In Figure 5, the geometry of the DM interaction in a generic T 1/3 M S 2 compound with a √ 3 × √ 3 superlattice is illustrated.…”

“…These spin textures are discussed further in later sections of this Perspective. 19,40 The MCAE is a special case of magnetic anisotropy that arises from SOC and is related to the crystal structure of a magnetic material. 39 Because of the lattice crystal field's inherent anisotropy, spins align preferentially along specific crystallographic directions, which are called the easy axes (or planes) of magnetization.…”

“…Among known magnetic intercalated TMDs, Fe-and Cr-intercalated NbS 2 and TaS 2 materials exhibit a wide range of behaviors depending on the intercalant's identity and stoichiometry. Their properties, which include sharp switching of magnetization, 14,15 low-current electrical switching of antiferromagnetic states, 13,16 and chiral spin textures, [17][18][19] have positioned these materials as potential candidates for spin-based electronic technologies (spin-tronics). From a fundamental perspective, these exotic magnetic phases have also motivated detailed investigations into the many-body physics underlying their behavior, and the correlations between the compositions and magnetic properties of these systems have made them attractive platforms to study structure-property relationships in solid-state materials.…”

“…13,16,23,24 Cr x NbS 2 and Cr x TaS 2 both exhibit chiral spin textures when x = 1/3, with different concentrations of topologically-protected magnetic solitons that evolve with field and temperature. [17][18][19]25,26 Key experimental findings for this family of materials are summarized, and future directions and open questions are discussed.…”