Collective Magnetic Behavior in Vanadium Telluride Induced by Self-Intercalation

Abstract

Self-intercalation of native magnetic atoms within the van der Waals (vdW) gap of layered two-dimensional (2D) materials provides a degree of freedom to manipulate magnetism in low-dimensional systems. Among various vdW magnets, the vanadium telluride is an interesting system to explore the interlayer order−disorder transition of magnetic impurities due to its flexibility in taking nonstoichiometric compositions. In this work, we combine high-resolution scanning transmission electron microscopy (STEM) analysis with density functional theory (DFT) calculations and magnetometry measurements, to unveil the local atomic structure and magnetic behavior of V-rich V 1+x Te 2 nanoplates with embedded V 3 Te 4 nanoclusters grown by chemical vapor deposition (CVD). The segregation of V intercalations locally stabilizes the self-intercalated V 3 Te 4 magnetic phase, which possesses a distorted 1T′-like monoclinic structure. This phase transition is controlled by the electron doping from the intercalant V ions. The magnetic hysteresis loops show that the nanoplates exhibit superparamagnetism, while the temperature-dependent magnetization curves evidence a collective superspin-glass magnetic behavior of the nanoclusters at low temperature. Using four-dimensional (4D) STEM diffraction imaging, we reveal the formation of collective diffuse magnetic domain structures within the sample under the high magnetic fields inside the electron microscope. Our results shed light on the studies of dilute magnetism at the 2D limit and on strategies for the manipulation of magnetism for spintronic applications.

Probing Functional Structures, Defects, and Interfaces of 2D Transition Metal Dichalcogenides by Electron Microscopy

“…It is noteworthy that these techniques possess multiple capabilities and have wide‐ranging applications, including super‐resolution imaging, [ 140c ] low‐dose imaging, [ 147 ] mapping of strain, [ 148 ] electric, [ 149 ] and magnetic field. [ 27a,150 ] Some of them have been introduced in previous review papers. [ 30,149a,151 ] In this discussion, we will focus specifically on the application of 4D‐STEM and DPC techniques for mapping the local electric and magnetic fields in TMDs, thereby enabling functional imaging of TMDs.…”

“…Guzman et al revealed the formation of diffuse magnetic domain structures in V 1+x Te 2 by 4D-STEM imaging, which originate from the collective magnetism of ensembles of magnetic V 3 Te 4 nanoclusters. [150] Figure 7i illustrates the reconstructed magnetic induction magnitude (left panel) and magnetic field vector (right panel) maps revealing the presence of nanometer-size clusters surrounded by a nonmagnetic background, and the formation of uniformly magnetized domains, respectively. To ensure the reconstructed contrast is intrinsically contributed by the local magnetic field of V x Te y domains, Guzman et al conducted control experiments on a nonmagnetic sample and vacuum.…”

“…i) Reconstructed magnetic induction magnitude (left panel) and magnetic field vector (right panel) maps of V 3 Te 4 domains obtained by 4D-STEM techniques. Reproduced with permission [150]. Copyright 2023, American Chemical Society.…”

Construction of a label-free electrochemical immunosensor based on a Co9S8/Co3C@C dual-heterojunction for the detection of diethylstilbestrol

“…Through the contact, electrons are transferred until the work functions are equal. 34,35 Chemical doping, 36 nanostructure engineering, 37 and construction of hybrids 38 are all viable strategies for fulfilling the fabrication of heterostructures. It consequently seems extremely positive to combine alternative construction approaches to create heterostructures.…”

2D Materials by Design: Intercalation of Cr or Mn between two VSe2 van der Waals Layers

“…For different concentrations, in-plane ordered 2 × 2, √3 × √3 R30°, or 2 × 1 superstructures are known . Previous studies of ultrathin pseudo 2D crystals of this class are based on known bulk phases or self-intercalation compounds (i.e., only one kind of TM). ,, Bulk-exfoliated sheets or thin films of these materials have demonstrated important phenomena, such as concentration-dependent magnetic anisotropy and skyrmion lattices in Cr 1+δ Te 2 , , magnetic properties of self-intercalated TaS 2 and in VSe 2 and VTe 2 , proposed superconductivity in Ni 1+δ Te 2 , layer-dependent magnetism in CrCuSe 2 , and demonstration of heteroepitaxy of CuCr 2 Te 4 . In contrast to these reports, a novel synthesis approach is discussed here that enables incorporation of various TMs between TMD sheets.…”