diamond (RG) is a ABC stacking multi-layer graphene, which is famous for its potential for exploring strong related electronic phenomena.Different from the distorted graphene layer of the Moore stripes, RG provides a non -distorted and simpler system to study the primary physics.
In view of this, Professor Yin Longjing, Hunan University, Professor Qin Zhihui, and Professor Wang Wenxiao of Hebei Normal University In -depth study of diamond graphene (RG), Focus on the electronic characteristics and correlations related to the layer, and fill the knowledge blank about how the electronic correlation between RG has evolved with the increase of layer thickness.The author uses a scanning tunnel microscope and spectrum (STM/STS) at a liquid nitrogen temperature to study the RG layer from three to nine layers.This study aims to clarify the dependence of layers on the number of low -energy flat bands and associated states. The results of the research show that the correlation effect is enhanced, especially at the six -layer threshold. Related research results are published in the latest issue Ology ".
[Objectives and spectral signs]
Author The use of Van Dehuas accumulation method to prepare high -quality RG samples on the hexagonal boron -nitride (HBN) to ensure the structure integrity and the least impurities .Figure 1 illustrates this part that shows the STM appearance of the sample, including a detailed atomic STM image (Figure 1A) and the six -layer RG sample (Figure 1b and 1C).The STM appearance shows a uniform and no impurities surface, and there is no observing the Great Moor Super Crystal. This is caused by RG and the underlying HBN deliberately dislocation.The key spectral features include the obvious state density (DOS) peak near the Fermi -energy level, which corresponds to the flat characteristics of RG. The flat band appears evenly on the large surface area, which means that the nano -level doping changes are the least.Figure 1D further emphasizes local DOS peaks related to flat and remote bands (marked as FB, RB1, and RB2), and Figure 1E depicts the uniformity of the space characteristics of these spectral characteristics.
Figure 1. The appearance and spectrum of diamond-shaped multi-layer graphene
[Layer -related energy band structure]
The evolution of the structure that can change with the number of RG layers .Figure 2 shows the DOS spectrum of different layers (from three to nine layers), which shows the correlation characteristics of the layer. As the number of layers increases, the flat -band peak becomes more obvious, indicating that the flat area in the kinetic space expands .This leads to a stronger DOS peak near the charge neutral point (CNP), especially in thicker RG samples, as shown in Figure 2A.As the number of layers increases, the measured flat bandwidth is slightly narrow, which means that the thickness of the thicker RG layer is better and the sample quality is higher (Figure 2B).In addition, with the increase of the interstitial coupling strength parameter (γ1) with the thickness of the thickness (Figure 2C), this behavior indicates that the electronic interaction in the thicker RG layer enhances .The theoretical calculation of the band -band structure displayed in Figure 2D and 2E is consistent with the results of the experimental observation, and confirmed that the increasing the number of layers, the increase of inter -layer interaction parameters increase .
Figure 2. The energy of the energy of the multi-layer graphene of the diamond surface
[Related status related to layer]
The author explores the related effect of the RG, Evaluate the electronic interaction when the flat belt is filled EssenceThey adjusted the fill state of the RG flat band by applying the back grid voltage to capture the evolution of the DOS peak under different doping.Figure 3 shows how the DOS peak in the three layers of RG transitions from a single peak at the time of full fill to a wide split peak when the semi -filling is, indicating that there is a associated state.It is worth noting that when the Fermi energy level is located in the flat belt, major changes have undergone the DOS summit, which is manifested as a peak division at the time of nearly half -filled (Figure 3A).A similar behavior was observed in a thicker layer, and the division energy enhanced with the layer.Figure 3B captures the gradual change of the DOS peak, and FIG. 3E illustrates the split phenomenon in different flat band filling states in the six layers of RG samples.The split value of cross-layer records changes between 50-80MEV, highlighting the significant relationship in thicker RG.These findings emphasize that the state of RG will not only continue to exist, but also becomes more and more stable as the number of layers increases, reaching the maximum related intensity in the six -layer RG (Figure 3F).
Figure 3. Dived dependence of flat LDOS Peak
Figure 4 explains the explanationElectronic correlation with electronic correlation in RG.Figures 4A and 4B show 3 layers (3L) to 9 -layer (9L) RG space to distinguish DOS equal value line diagrams and specific DOS spectrum .These spectra reveals the obvious peak division mode in the DOS, which can be observed when the flat band is partially filled.This peak split phenomenon is the key indicator of strong electronic correlations caused by flat tiles in multi -layer graphene .The quantitative measurement results of the flat -band peak and split energy of different layers are shown in Figure 4C.The split energy value increased from 3L to 6L, and reached the maximum value (~ 80MEV), and then decreased slightly as the number of layers (7L and above).The peak value of the 6 -layer related intensity is consistent with the theoretical model. The theoretical model predicts that due to the balance between the state density (DOS) and the electronic shielding effect at the neutral point (CNP), the critical thickness will optimize the related effect.In thicker RG, the higher DOS at CNP will increase electron interaction, but this will be offset by the enhanced shielding, which will cause the maximum correlation on the sixth floor.The author provides the theoretical calculation of related energy gaps in different layers of level -level bands by using the average field theory (MFT) and density pan -letter theory (DFT). Large split energy in 6L RG comes from layer anti -ferr magnetic (LAF) insulation state at the charge neutral point, as well as possible spin or valleys in the light doped area .
Figure 4. layer dependence of electronic correlation
[Summary]
STM/STS measurement, this article studies With the changes in the number of layers, the evolution of the RG band structure and its related phase .The discovered flat band and inter -layer jump intensity provides important information for the basic belt structure structure of the multi -layer RG.In particular, the author discovered the correlation between layers, which continued to exist at the temperature of liquid nitrogen, and its maximum interaction strength was 6L.The correlations observed in the multi -layer of N & LT; 10RG reveals several intriguing aspects and can stimulate further research. (1) The author clearly determines the layer dependence of LAF status on the CNP, which is performed elusive in the previous RG (3L, 4L, 5L, and thick layer). (2) Such obvious correlation at the temperature of liquid nitrogen is very surprising , although this may be affected by measurement.In view of this, multi -layer RG is a very promising system, which can carry the collective phenomenon that can be highly accessible and resist thermal fluctuations. (3) superconducts in RG have only found in slightly mixed 3Ls. .The research results of this article show that in 3
Source: Minister of Science
Statement: Only represent the authors personal point of view, the authors level is limited.Raiders!not"
