Abstract:We study the Ruderman-Kittel-Kasuya-Yosida interaction between magnetic impurities embedded in p-doped transition metal dichalcogenide triangular flakes. The role of underlying symmetries is exposed by analyzing the interaction as a function of impurity separation along zigzag and armchair trajectories, in specific parts of the sample. The large spin-orbit coupling in these materials produces strongly anisotropic interactions, including a Dzyaloshinskii-Moriya component that can be sizable and tunable. We cons… Show more
“…positioned on the edge of the LTMDs [96]. A similar oscillation trend from RKKY was also found between the distance of impurities and the interaction strength in the p-doped LTMD monolayer [97]. Therefore, the symmetry of the whole system also affects the final magnetism.…”
Section: Analysis From Electronic Structuressupporting
confidence: 64%
“…A magnetic dipole is formed, and the polarization decays in oscillations based on the distance from the dopant. Such a trend is well reproduced in the dually doped ILC systems [97,98]. On the other hand, in a dilute-doped system, the local magnet is strong enough, but the couplings from the neighboring supercells are general neglected.…”
Pioneering explorations of the two-dimensional (2D) inorganic layered crystals (ILCs) in electronics have boosted low-dimensional materials research beyond the prototypical but semi-metallic graphene. Thanks to species variety and compositional richness, ILCs are further activated as hosting matrices to reach intrinsic magnetism due to their semiconductive natures. Herein, we briefly review the latest progresses of manipulation strategies that introduce magnetism into the nonmagnetic 2D and quasi-2D ILCs from the first-principles computational perspectives. The matrices are concerned within naturally occurring species such as MoS 2 , MoSe 2 , WS 2 , BN, and synthetic monolayers such as ZnO and g-C 2 N. Greater attention is spent on nondestructive routes through magnetic dopant adsorption; defect engineering; and a combination of doping-absorbing methods. Along with structural stability and electric uniqueness from hosts, tailored magnetic properties are successfully introduced to low-dimensional ILCs. Different from the three-dimensional (3D) bulk or zero-dimensional (0D) cluster cases, origins of magnetism in the 2D space move past most conventional physical models. Besides magnetic interactions, geometric symmetry contributes a non-negligible impact on the magnetic properties of ILCs, and surprisingly leads to broken symmetry for magnetism. At the end of the review, we also propose possible combination routes to create 2D ILC magnetic semiconductors, tentative theoretical models based on topology for mechanical interpretations, and next-step first-principles research within the domain.
“…positioned on the edge of the LTMDs [96]. A similar oscillation trend from RKKY was also found between the distance of impurities and the interaction strength in the p-doped LTMD monolayer [97]. Therefore, the symmetry of the whole system also affects the final magnetism.…”
Section: Analysis From Electronic Structuressupporting
confidence: 64%
“…A magnetic dipole is formed, and the polarization decays in oscillations based on the distance from the dopant. Such a trend is well reproduced in the dually doped ILC systems [97,98]. On the other hand, in a dilute-doped system, the local magnet is strong enough, but the couplings from the neighboring supercells are general neglected.…”
Pioneering explorations of the two-dimensional (2D) inorganic layered crystals (ILCs) in electronics have boosted low-dimensional materials research beyond the prototypical but semi-metallic graphene. Thanks to species variety and compositional richness, ILCs are further activated as hosting matrices to reach intrinsic magnetism due to their semiconductive natures. Herein, we briefly review the latest progresses of manipulation strategies that introduce magnetism into the nonmagnetic 2D and quasi-2D ILCs from the first-principles computational perspectives. The matrices are concerned within naturally occurring species such as MoS 2 , MoSe 2 , WS 2 , BN, and synthetic monolayers such as ZnO and g-C 2 N. Greater attention is spent on nondestructive routes through magnetic dopant adsorption; defect engineering; and a combination of doping-absorbing methods. Along with structural stability and electric uniqueness from hosts, tailored magnetic properties are successfully introduced to low-dimensional ILCs. Different from the three-dimensional (3D) bulk or zero-dimensional (0D) cluster cases, origins of magnetism in the 2D space move past most conventional physical models. Besides magnetic interactions, geometric symmetry contributes a non-negligible impact on the magnetic properties of ILCs, and surprisingly leads to broken symmetry for magnetism. At the end of the review, we also propose possible combination routes to create 2D ILC magnetic semiconductors, tentative theoretical models based on topology for mechanical interpretations, and next-step first-principles research within the domain.
“…Although we had found 2D behavior for the interaction between impurities in the interior of flakes before [47], and some evidence of long range interaction for hybridization near the edges [48], we present here the full systematics.…”
Section: Introductionmentioning
confidence: 99%
“…We use 2λ = 150 meV, in good agreement with DFT calculations [5,45] and experimental values (152 meV [53], 138 meV [54] and 145 meV [55]). With this Hamiltonian and the right choice of boundaries, one can construct a flake like the triangle we consider [48,47,52]. Others TMDs can be similarly modeled, taking the onsite, hopping and SOC parameters from Tables II and III in [45].…”
Section: Model and Approachmentioning
confidence: 99%
“…The total effective interaction is a competition between in-plane J XX (= J Y Y ), Ising J ZZ , and DzyaloshinskiiMoriya J DM terms. In TMDs the Ising and DM terms are generated by the SOC; their competition has been recently discussed for bulk samples [31,33] and flakes [48,47]. To calculate the effective J's in our finite sample, we take the difference of triplet and singlet configurations of impurities in the electronic ground state [58,59] as…”
Abstract. We study the Ruderman-Kittel-Kasuya-Yosida interaction between two magnetic impurities connected to the edges of zigzag-terminated MoS 2 flakes. When the impurities lie on the edges of the flake, the effective exchange interaction exhibits sizable noncollinear Dzyaloshinskii-Moriya character that competes with a strong Ising coupling. We analyze the characteristic decay exponent for doping levels inside the band gap of the infinite layer, corresponding to edge states of the flake at the Fermi level. The characteristic exponents show sub-twodimensional (sub-2D) behavior for these band fillings, with decays much slower than quadratic. The Ising interaction has effectively one-dimensional (1D) long range, while the noncollinear component that grows for short impurity separation becomes comparable in magnitude. The resulting tunable exchange interaction on these systems opens the way for the study of interesting phases of impurity arrays with long-range stable helical order.arXiv:1607.08553v3 [cond-mat.mes-hall]
A theoretical investigation on electronic states in triangular MoS2 quantum dots of different sizes is performed within density functional theory first‐principles formalism. Herein, the associated interband optical response from real and imaginary parts of the dielectric function is calculated. The study considers both undoped and Al‐, Si‐, and P‐doped systems. Spin‐related magnetic properties are considered through the evaluation of total magnetic moment. It is revealed that small enough structures have a semiconductor character, but evolve to seemingly half‐metallic with increasing dot size. Nonzero magnetic response is attributed to edge effects. Magnetic behavior of doped systems deviates from the linear dependence of the total magnetic moment with size occurring in the undoped case, producing situations with higher total momentum values. It is found that increasing the doping density may have certain influence over total magnetic moment response of the structures, although edge dominance is kept all the way. Optical properties are not as sensitive to incident light polarization, but they actually do with regard to the particular spin orientation. Calculation for the refraction index in the triangular quantum dots shows values still below the accepted in the MoS2 monolayer case, although a correct trend of variation is reported in this sense.
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