Self‐Intercalated Magnetic Heterostructures in 2D Chromium Telluride

Abstract

Emerging 2D magnetic heterojunctions attract substantial interest due to their potential applications in spintronics. Achieving magnetic phase engineering with structural integrity in 2D heterojunctions is of paramount importance for their magnetism manipulation. Herein, starting with chromium ditelluride (CrTe2) as the backbone framework, various lateral and vertical magnetic heterojunctions are obtained via self‐intercalated 2D chromium telluride (CrxTey). A Cr2Te3‐Cr5Te8 lateral heterojunction prototype is demonstrated for the manipulation of magnetic moments under different magnitudes of magnetic excitation, showing a sharply stepped hysteresis loop with a dual spin‐flip transition at high Curie temperatures up to 150 and 210 K by magneto‐optical Kerr measurement. High‐resolution scanning transmission electron microscopy and first‐principles calculations reveal a preferred random location of Cr intercalants at the phase boundary, allowing lowering energy associated with crystal field splitting. The overall structural rigidity of chromium‐telluride heterostructure with magnetic phase decoupled behaviors is promising for 2D spintronic devices.

Mechanism Regulating Self-Intercalation in Layered Materials

“…Since Richard Feynman proposed the possibility of direct manipulation of individual atoms as a powerful way for materials synthesis and discovery more than 70 years ago, precise control of lattice structures and compositions of materials has been a focus of nanoscience and nanotechnology toward achieving engineered properties and functionalities. Such control is especially relevant and viable in two-dimensional (2D) materials build via van der Waals (vdW) assembly of a number of vertically stacked multilayers with designable properties. − Of particular interest is the vdW gap, defined as an angstrom-scale emptiness between adjacent layers in the multilayers, which has been exploited to favorably host a diverse range of foreign species via intercalation. − Successful intercalants include commonly used metal atoms ranging from alkali to noble metals and a series of organic molecules. − In addition to introducing inherent properties to systems, the intercalants offer charge transfers to 2D materials, which may significantly modify interlayer interactions, thereby opening unprecedented opportunities of potential applications in a variety of domains, such as electronics, , thermoelectrics, , catalysis, − and energy storage. − Among reported intercalated materials, layered self-intercalated materials, where intercalated metal atoms are native to host 2D materials, have been intensively studied. − In contrast to intercalation of foreign atoms that usually requires postgrowth treatment and is difficult to yield long-range crystalline phase, self-intercalation can be directly achieved with controlled stoichiometry by growing 2D materials under conditions involving high chemical potential of metals. ,− Moreover, self-intercalation avoids uncontrollable chemical doping issues that are often encountered when foreign atoms react with the hosting materials. A recent experiment reported synthesis of a class of ultrathin, covalently bonded 2D materials with well-defined stoichiometries and composition-tunable properties by self-intercalation of native atoms into bilayer transition metal dichalcogenides, MX 2 (M = transition metal and X = S, Se, Te, etc.)…”

The electronic and optical properties of silicon doped on arsenic and antimony nanotubes: a first-principles study

“…Yuan et al 44 demonstrated that a Kubo gap δ can be achieved with a two-dimensional (2D) metallic transition metal dichalcogenide nanocluster embedded in a semiconducting polymorph, which shows a strong polarization catastrophe while simultaneously maintaining its bond integrity, which is absent in traditional δ-gapped 3D clusters. Various lateral and vertical magnetic heterojunctions can be obtained via self-intercalation of Cr atoms in 2D Cr x Te y , 45 and their electronic band structures are obtained mainly by splitting of the 3d orbitals of Cr atom due to van der Waals forces, which is different from that of p orbitals owing to interatomic interaction. Semi-metallic γ-GeSe with absorbed Li 46 causes negligible changes in the p-orbitals of Ge and Se except for the upward shift of the Fermi level to the conduction band and semi-metallic γ-GeSe under strain, 47 which results from competing bands at the band edges.…”

Magnetism of two-dimensional chromium tellurides

“…have prepared lateral Cr 2 Te 3 -Cr 5 Te 8 heterojunction in a one-pot CVD method. 112 The lateral heterojunction displays controllability in magnetic moments by an external field, suggested by the sharp steps in the hysteresis loop. The decoupling effect, arising from the random arrangement of Cr intercalants, is predicted to be the reason behind the flipping behavior.…”