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  • 1
    Online Resource
    Online Resource
    Magnetic exchange interaction in two-dimensional lattice under generalized Bloch condition
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2022
    In:  Acta Physica Sinica Vol. 71, No. 1 ( 2022), p. 017105-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 71, No. 1 ( 2022), p. 017105-
    Abstract: Two-dimensional magnetic material which has been rapidly developed in recent years, has potential applications in developing spintronic devices. In order to understand the magnetic properties of two-dimensional magnetic materials, it is necessary to comprehend the magnetic interaction which is estimated by the exchange parameters between the magnetic atoms. The calculation of the magnetic exchange parameters is based on the first-principle. The commonly used method of determining the values of exchange parameters is energy-mapping. However, this method has some disadvantages. In this paper, the spin-spiral dispersion relationship is derived under the Heisenberg interaction and the Dzyaloshinskii-Moriya (DM) interaction through the generalized Bloch condition of three common two-dimensional magnetic structures: a tetragonal structure, a hexagonal structure in which the cell contains one magnetic atom, a hexagonal structure in which the cell contains two magnetic atoms. The magnetic exchange parameters of some materials are calculated through the first principle. These materials are MnB, VSe〈sub〉2〈/sub〉 MnSTe and Cr〈sub〉2〈/sub〉I〈sub〉3〈/sub〉Cl〈sub〉3〈/sub〉. Among them, the MnSTe and Cr〈sub〉2〈/sub〉I〈sub〉3〈/sub〉Cl〈sub〉3〈/sub〉 are two-dimensional Janus materials, which means that they have space-reversal symmetry broken, that is why there is DM interaction in the system.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.71.20211317
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2022
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  • 2
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    Online Resource
    Magnetic and eletronic transport properties in n-type diluted magnetic semiconductor Ge〈sub〉0.96–x〈/sub〉Bi〈sub〉x〈/sub〉Fe〈sub〉0.04〈/sub〉Te film
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2019
    In:  Acta Physica Sinica Vol. 68, No. 10 ( 2019), p. 107501-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 68, No. 10 ( 2019), p. 107501-
    Abstract: The epitaxial thin films of Ge〈sub〉0.96−〈i〉x〈/i〉〈/sub〉Bi〈sub〉〈i〉x〈/i〉〈/sub〉Fe〈sub〉0.04〈/sub〉Te are deposited on BaF〈sub〉2〈/sub〉 substrates by using pulsed laser deposition technique. The thin films with three different compositions i.e. Ge〈sub〉0.8〈/sub〉Bi〈sub〉0.2〈/sub〉Te, Ge〈sub〉0.76〈/sub〉Bi〈sub〉0.2〈/sub〉Fe〈sub〉0.04〈/sub〉Te, and Ge〈sub〉0.64〈/sub〉Bi〈sub〉0.32〈/sub〉Fe〈sub〉0.04〈/sub〉Te are prepared in this wok. Their high-quality epitaxy and crystallinity are confirmed by X-ray diffraction and atomic force microscopy. According to the measurements of Hall effect variation, we find that each of all curves exhibits a negative slope for the different films as the temperature varies from low temperature to room temperature, indicating that Ge〈sub〉0.96−〈i〉x〈/i〉〈/sub〉Bi〈sub〉〈i〉x〈/i〉〈/sub〉Fe〈sub〉0.04〈/sub〉Te films are n-type material because the substitution of Bi for Ge makes the carriers change from holes into electrons. Temperature dependence of resistivity confirms that the electronic transport behavior for each of Ge〈sub〉0.96−〈i〉x〈/i〉〈/sub〉Bi〈sub〉〈i〉x〈/i〉〈/sub〉Fe〈sub〉0.04〈/sub〉Te thin films exhibits a typical semiconductor characteristic. From the measurements of temperature dependence of electronic transport under various external magnetic fields, we find that the Ge〈sub〉0.64〈/sub〉Bi〈sub〉0.32〈/sub〉Fe〈sub〉0.04〈/sub〉Te thin film shows some magnetoresistive effect while other composition films do not possess such a property. Based on the linear fitting of temperature dependence of magnetic susceptibility in high temperature and low temperature region, the magnetic property of Ge〈sub〉0.64〈/sub〉Bi〈sub〉0.32〈/sub〉Fe〈sub〉0.04〈/sub〉Te thin film changes from 253 K. Together with the study of magnetic susceptibility curve in the paramagnetic region, the Curie-Weiss temperature is determined to be 102 K. At a low temperature of 10.0 K, we observe an obvious ferromagnetic hystersis loop in Ge〈sub〉0.64〈/sub〉Bi〈sub〉0.32〈/sub〉Fe〈sub〉0.04〈/sub〉Te instead of in Ge〈sub〉0.76〈/sub〉Bi〈sub〉0.2〈/sub〉Fe〈sub〉0.04〈/sub〉Te thin film. These results imply that the increase of Bi dopant is main reason for the establishment of ferromagnetic ordering state. The carrier concentration increases and thus promotes the carriers transporting the Ruderman-Kittel-Kasuya-Yoshida interaction, thereby leading to the separated Fe ions producing the magnetic interaction and forming an n-type diluted magnetic semiconductor.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.68.20190019
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2019
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  • 3
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    Online Resource
    First-principles study of role of Kitaev interaction in monolayer 1〈i〉T〈/i〉-CoI〈sub〉2〈/sub〉
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2023
    In:  Acta Physica Sinica Vol. 72, No. 24 ( 2023), p. 247101-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 72, No. 24 ( 2023), p. 247101-
    Abstract: Kitaev interactions, which are bond-related anisotropic interactions induced by spin-orbit coupling (SOC), may produce quantum spin liquid states in two-dimensional (2D) magnetic hexagonal lattices such as RuCl 〈 sub 〉 3 〈 /sub 〉 . Generally, the strong SOCs in these materials come from heavy metal elements such as Ru in RuCl 〈 sub 〉 3 〈 /sub 〉 . In recent years, some related studies have shown the presence of Kitaev effects in some 2D monolayers of ortho-octahedral structures containing heavy ligand elements, such as CrGeTe 〈 sub 〉 3 〈 /sub 〉 and CrSiTe 〈 sub 〉 3 〈 /sub 〉 . However, there are relatively few reports on the Kitaev interactions in 2D monolayer 1 〈 i 〉 T 〈 /i 〉 structures. In this paper, we calculate and analyse the atomic and electronic structures of 1 〈 i 〉 T 〈 /i 〉 -CoI 〈 sub 〉 2 〈 /sub 〉 and the Kitaev interactions contained therein by the first-principles calculation program VASP. The structure of 1 〈 i 〉 T 〈 /i 〉 -CoI 〈 sub 〉 2 〈 /sub 〉 is a triangular lattice with an emphasis on the coordinating element I. The energy dispersion relation 〈 inline-formula 〉 〈 tex-math id="M2" 〉 \begin{document}$ {E}_{{\mathrm{S}}}\left(\boldsymbol{q}\right)={E}_{{\mathrm{N}}+{\mathrm{S}}}\left(\boldsymbol{q}\right)-{E}_{{\mathrm{N}}}\left(\boldsymbol{q}\right) $\end{document} 〈 /tex-math 〉 〈 alternatives 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M2.jpg"/ 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M2.png"/ 〉 〈 /alternatives 〉 〈 /inline-formula 〉 for the contained Kitaev action is isolated by calculating the energy dispersion relation 〈 inline-formula 〉 〈 tex-math id="M3" 〉 \begin{document}$ {E}_{{\mathrm{N}}}\left(\boldsymbol{q}\right) $\end{document} 〈 /tex-math 〉 〈 alternatives 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M3.jpg"/ 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M3.png"/ 〉 〈 /alternatives 〉 〈 /inline-formula 〉 for the spin-spiral of monolayer CoI 〈 sub 〉 2 〈 /sub 〉 without SOC and the energy dispersion relation 〈 inline-formula 〉 〈 tex-math id="M4" 〉 \begin{document}$ {E}_{{\mathrm{N}}+{\mathrm{S}}}\left(\boldsymbol{q}\right) $\end{document} 〈 /tex-math 〉 〈 alternatives 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M4.jpg"/ 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M4.png"/ 〉 〈 /alternatives 〉 〈 /inline-formula 〉 considering SOC by using the generalized Bloch condition combined with the spin-spiral method. The parameters of the Heisenberg exchange interaction induced by the SOC are obtained by fitting the dispersion law of the 〈 inline-formula 〉 〈 tex-math id="M5" 〉 \begin{document}$ {E}_{{\mathrm{S}}}\left(\boldsymbol{q}\right) $\end{document} 〈 /tex-math 〉 〈 alternatives 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M5.jpg"/ 〉 〈 graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="24-20230909_M5.png"/ 〉 〈 /alternatives 〉 〈 /inline-formula 〉 to the Kitaev exchange interaction with the parameters of the Kitaev exchange interaction. The fitted curves obtained with the fitted parameters are in good agreement with the calculated values, indicating the accuracy of our calculations. Calculated fits show that the monolayer CoI 〈 sub 〉 2 〈 /sub 〉 is dominated by Heisenberg action, with the third nearest neighbour having the largest absolute value of 〈 i 〉 J 〈 /i 〉 at –1.81 meV. In addition to this, there are strong Kitaev interactions in the monolayer CoI 〈 sub 〉 2 〈 /sub 〉 , where 〈 i 〉 Γ 〈 /i 〉 〈 sub 〉 1 〈 /sub 〉 reaches 1.09 meV. We predict that the Kitaev interactions are universally applicable to transition metal triangular lattices with 1 〈 i 〉 T 〈 /i 〉 structure. It is shown that the CoI 〈 sub 〉 2 〈 /sub 〉 can be used as an alternative material for Kitaev and lays a theoretical foundation for exploring Kitaev interactions in other 2D magnetic materials.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Article
    DOI: 10.7498/aps.72.20230909
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2023
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  • 4
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    Online Resource
    Dzyaloshinsky-Moriya interaction in -(Zn, Cr)S(111) surface: First principle calculations
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2018
    In:  Acta Physica Sinica Vol. 67, No. 13 ( 2018), p. 137101-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 67, No. 13 ( 2018), p. 137101-
    Abstract: According to density functional theory calculations, we elucidate the atomic and electronic structure of -(Zn, Cr)S(111) surface. The magnetic interaction between Cr atoms is via S atoms close to the Cr layer. This interaction is shown by the analysis of spin charge contour plot and partial density of states (DOS) of each atom. The DOSs of other S atoms are non magnetic and have no magnetic exchange with the Cr layer. E(q) and E(-q) are the dispersions between energy E and wave vector q of spin spiral in the opposite directions. They are calculated with generalized Bloch equations and all the magnetic moments of Cr atoms are arranged in the plane perpendicular to the -(Zn, Cr)S(111) film. The differences between E(q) and E(-q) are caused by the interface of -(Zn, Cr)S(111), where the symmetry of space perpendicular to the film is broken. Effective Heisenberg exchange interaction (HBI) and Dzyaloshinsky-Moriya interaction (DMI) parameters between different neighbors (Ji and di) are derived by well fitting the ab initio spin spiral dispersion E(q) to HBI with DMI model and E(q)-E(-q) to DMI model, respectively. The J2 plays a major role with a large negative value of -9.04 meV. The J1 is about 2/5 of J2, and J3 is about 1/4 of J2 with positive value. The DMI d1 is -0.53 meV, and d2 is 0.07 meV. With these HBI parameters, E(0) is the largest one at which -(Zn, Cr)S(111) has no ferromagnetic interface. The E(q) has its lowest energy with the q at M=b1/2 in the first Brillouin zone. Hence, -(Zn, Cr)S(111) is an M-type antiferromagnetic (AFM) material. In this type of AFM configuration, magnetic moments of Cr atom in a line along b2 are parallel to each other, and antiparallel to the magnetic moments in adjacent lines. The E(q) at K=b1/2+ b2/2 is almost as large as that at point. The value of DMI parameter d1 is about 1/5 of that on Co/Pt3 interface and 1/2 of Co/graphene. However, it is a negative number, which shows the clockwise chirality. The -(Zn, Cr)S(111) interface has obvious DMI, and skyrmion may be formed at this transition-metal/semiconductor (TM/S) interface. It is a good option to search for DMI in different kinds of TM/S heterojunctions. The material that combines the advantage of heterojunction, and DMI may have new magnetic phenomenon, which is usefulfor the magnetic storage. This paper enriches the research on DMI.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.67.20180342
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2018
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  • 5
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    Online Resource
    First principle study of weak Dzyaloshinsky-Moriya interaction in Co/BN surface
    Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences ; 2018
    In:  Acta Physica Sinica Vol. 67, No. 11 ( 2018), p. 117102-
    Details
    In: Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 67, No. 11 ( 2018), p. 117102-
    Abstract: Based on density functional theory calculations, we elucidate the atomic and electronic structures of Co atom of hexgonal BN (Co/h-BN). The interaction between magnetic moments of Co atoms is realized through Co-N_-B_ grid, which is indicated by the analysis of spin charge contour plot and partial density of states of each atom, where and denote the site of B or N atom close to and away from Co atom, respectively. Then the dispersion relations E(q) and E(-q) (q denotes the direction vector of spin spiral) between energy and wave vector of spin spiral in the opposite directions are calculated with generalized Bloch equations. In the incommensurate spin spiral calculations, all the magnetic moments of Co atom are arranged in the same plane that is perpendicular to the Co/h-BN film. The difference between E(q) and E(-q) is caused by the interface of Co/h-BN, where the symmetry of space perpendicular to the film is broken. Moreover, the effective Heisenberg exchange interaction (HBI) and Dzyaloshinsky-Moriya interaction (DMI) parameters between different neighbors (Ji and di) are derived by well fitting the ab initio magnon dispersion E(q) to HBI with DMI model and E(q)-E(-q) to DMI model, respectively. The J1 has a negative value and plays a major role, J3 is one order of magnitude smaller than J1, and other parameters are close to zero. Hence, Co/h-BN is triangular antiferromagnetic material with the q at k point in the first Brillouin zone. However, the spin spiral with the q at M point is only 2 meV larger than the basic state with the only negative J1 and smaller positive J2. The DMI is not shown in this interface with d1 and d2 close to zero. Based on the non DMI character and its stability in air, h-BN can be capped on other DMI interfaces. The reason that the DMI in Co/h-BN is much smaller than in Co/Gra is much larger height between Co and h-BN. It is 0.192 nm for h-BN but it is 0.156 nm for Co/Gra. We may reduce the height to enhance the DMI by other ways, such as adding electrical and magnetic fields in the future.
    Type of Medium: Online Resource
    ISSN: 1000-3290 , 1000-3290
    URL: Journal
    URL: Article
    DOI: 10.7498/aps
    DOI: 10.7498/aps.67.20180337
    Language: Unknown
    Publisher: Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
    Publication Date: 2018
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