Density functional theory (DFT) calculations of the energy of magnetic anisotropy for diluted ferromagnetic semiconductor GeMnTe were performed using using OpenMX package with fully relativistic pseudopotentials. The influence of hole concentration and magnetic ion neighborhood on magnetic anisotropy energy is presented. Analysis of microscopic mechanism of magnetic anisotropy is provided, in particular the role of spin-orbit coupling, spin polarization and spatial changes of electron density are discussed. The calculations are in accordance with the experimental observation of perpendicular magnetic anisotropy in rhombohedral GeMnTe (111) thin layers.
We have employed one of the well-known many-body techniques, density functional theory plus dynamical mean-field theory (DFT + DMFT), to investigate the electronic structure of ferromagnetic monolayer CrI3 as a function of temperature and hole-doping concentration. The computed magnetic susceptibility follows the Curie's law, indicating that the ferromagnetism of monolayer CrI3 originates from localized magnetic moments of Cr atoms rather than Stoner-type itinerant ones. The DFT + DMFT calculations show a different coherent temperature for each spin component, demonstrating apparent strong spi…
Among the numerous 2D system that can be prepared via exfoliation, iron phosphorus trisulfide (FePS3) attracts a lot of attention recently due to its broad-range photoresponse, its unusual Ising-type magnetic order and possible applications in spintronic nano-devices. Despite various experimental and theoretical-computational reports, there are still uncertainties in identifying its magnetic ground state. In this paper, we investigate the structural and magnetic properties of single-layer FePS3 by using Density Functional Theory. Our findings show that orbital ordering leads to a variation in …
CaCo2As2 is a unique itinerant system having strong magnetic frustration. Here we report the effect of electron doping on the physical properties resulting from Ni substitutions for Co. The A-type antiferromagnetic transition temperature TN = 52 K for x = 0 decreases to 22 K with only 3 percent Ni substitution and is completely suppressed for x > 0.11. For 0.11 < x < 0.52 strong ferromagnetic (FM) fluctuations develop as revealed by magnetic susceptibility chi(T) measurements. Heat-capacity Cp(T) measurements reveal the presence of FM quantum spin fluctuations for 0.11 < x < 0.52. Our density-…
Fe$_2$P alloys have been identified as promising candidates for magnetic refrigeration at room-temperature and for custom magnetostatic applications. The intent of this study is to accurately characterize the magnetic ground state of the parent compound, Fe$_2$P, with two spectroscopic techniques, $μ$SR and NMR, in order to provide solid bases for further experimental analysis of Fe$_2$P-type transition metal based alloys. We perform zero applied field measurements using both techniques below the ferromagnetic transition $T_C=220~\mathrm K$. The experimental results are reproduced and interpre…
Dirac-Electron Behavior for Spin-Up Electrons in Strongly Interacting Graphene on Ferromagnetic Mn$_5$Ge$_3$
提出了一种在强铁磁材料Mn $_5$ Ge $_3$上通过Mn嵌入石墨烯-Ge（111）界面合成石墨烯的方法。根据密度泛函理论计算，石墨烯在这种强相互作用体系中表现出石墨烯衍生的$π$带的大的交换分裂。在这种情况下，只有石墨烯中的自旋向上的电子在费米能级和K点附近保持了Dirac电子的特征，而自旋向下的电子则没有检测到这种行为。所研究的gr/FM-Mn $_5$ Ge $_3$界面可以在半导体Ge上制备，这一独特的特征可以导致其在自旋电子学中的应用。
Ferromagnetic Epitaxial μ-Fe$_{2}$O$_{3}$ on β-Ga$_{2}$O$_{3}$: A New Monoclinic form of Fe$_{2}$O$_{3}$
在这里，我们证明了一个新的单斜氧化铁相（μ-Fe $_{2}$ O $_{3}$），外延生长稳定的（010）β-Ga $_{2}$ O $_{3}$。密度泛函理论（DFT）计算发现，独立的μ-Fe $_{2}$ O $_{3}$的晶格参数在β-Ga $_{2}$ O $_{3}$的晶格参数的约1%以内，并且其形成能与天然丰富的Fe $_{2}$ O $_{3}$多型体相当。采用等离子体辅助分子束外延生长了μ-Fe $_{2}$ O $_{3}$ /β-Ga $_{2}$ O $_{3}$超晶格，高分辨X射线衍射（XRD）结果表明，μ-Fe $_{2}$ O $_{3}$层与衬底晶格匹配。测得的3.12 $\pm$ 0.4 Ω的面外（b）晶格参数与预测的晶格常数一致，并且原子分辨率扫描透射电子显微镜（STEM）图像证实μ-Fe $_{2}$ O $_{3}$层与β-Ga $_{2}$ O $_{3}$的完全配准。最后，密度泛函理论模拟预测，体相μ-$_{2}$ O $_{3}$是反铁磁的，而μ-$_{2}$ O $_{3}$和β-$_{2}$ O $_{3}$之间的界面区域导致界面Fe $^{3+}$阳离子选择性占据四面体位置之间的铁磁耦合.通过SQUID测量观察到的磁滞持续到室温，与计算预测的界面磁性一致。
The investigation of finite temperature properties using Monte-Carlo (MC) methods requires a large number of evaluations of the system's Hamiltonian to sample the phase space needed to obtain physical observables as function of temperature. DFT calculations can provide accurate evaluations of the energies, but they are too computationally expensive for routine simulations. To circumvent this problem, machine-learning (ML) based surrogate models have been developed and implemented on high-performance computing (HPC) architectures. In this paper, we describe two ML methods (linear mixing model a…
In search of the ferromagnetic insulators for spintronic device applications, we have studied the electronic, optical, and magnetic properties ofLa2CrNiO6(LCNO) using the first principle density functional theory (DFT)and monte carlo simulation technique. Firstly, we have adopted the sol-gel method for preparation of LCNO and refined the X-ray diffracted value using the fullprof suite under the Rietveld mechanism. The obtained orthorhombic Pbnm and cubic Fm-3m space groups are used as the input of the DFT calculations. Both the structures have shown the half metallicity and insult-ing bandgap …
We present a first-principles investigation of the structural, electronic, and magnetic properties of pyrolusite ($β$-MnO$_2$) using conventional and extended Hubbard-corrected density-functional theory (DFT+$U$ and DFT+$U$+$V$). The onsite $U$ and intersite $V$ Hubbard parameters are computed using linear-response theory in the framework of density-functional perturbation theory. We show that while the inclusion of the onsite $U$ is crucial to describe the localized nature of the Mn($3d$) states, the intersite $V$ is key to capture accurately the strong hybridization between neighboring Mn($3…
Magnetic layered ternary chalcogenides hold great promise for future spin-optoelectronic devices in the two dimensional limit. Understanding how the properties of the materials are impacted by magnetic ordering and the spin-orbit interactions is critically needed information for the development of applications. Ultrafast transient reflectance (TR) and photocurrent (PC) spectroscopies are combined with ab initio density functional theory (DFT) calculations to investigate the band structure and photoresponse of a layered magnetic semiconductor CrSiTe3 (CST) nanosheet in the paramagnetic (PM, 300…
We present a computational approach for electronically correlated metallic surfaces and interfaces, which combines Density Functional and Dynamical Mean Field Theory using a multi-orbital perturbative solver for the many-body problem. Our implementation is designed to describe ferromagnetic metallic thin films on a substrate. The performances are assessed in detail for a Fe monolayer on a W(110) substrate, a prototypical nanoscale magnetic system. Comparing our results to photoemission data, we find qualitative and quantitative improvements in the calculated spectral function with respect to t…
Spin-Dependent Nonorthogonal Generalized Wannier Functions and their Integration with PAW and Hubbard Corrections in Linear-Scaling DFT
University of Warwick（华威大学）；University of Southampton（南安普顿大学）；Trinity College Dublin, The University of Dublin（都柏林三一学院，都柏林大学）；Gdańsk University of Technology（格但斯克理工大学）
We have presented the synthesis, structural, and magnetic properties from the experimental point of view. Then we verified our experimental observation by studying the electronic and magnetic properties of Al-doped LaMnO3 from the first principle density functional theory (DFT) and Monte-Carlo simulation. We have synthesized the LaAlxMn1-xO3 (x= 0.05, 0.15, 0.25) and performed the Rietveld refinement of XRD data to determine the lattice parameters. To see the mixed valance of Mn-ion, we performed the XPS of 25% Al-doped material. The magnetic study shows the ferromagnetic transition of these m…
We present a systematic study of the electronic and magnetic properties of two-dimensional ordered alloys, consisting of two representative hosts (MnPS$_3$ and NiPS$_3$) of transition metal phosphorus trichalcogenides doped with $3d$ elements. For both hosts our DFT+U calculations are able to qualitatively reproduce the ratios and signs of all experimentally observed magnetic couplings. The relative strength of all antiferromagnetic exchange couplings, both in MnPS$_3$ as well as in NiPS$_3$, can successfully be explained using an effective direct exchange model: they reveal that the third-nei…
Interface induced states at the boundary between a 3D topological insulator Bi$_2$Se$_3$ and a ferromagnetic insulator EuS
采用相对论密度泛函理论（DFT）方法研究了沉积在铁磁绝缘体（FMI）EuS衬底上的拓扑绝缘体（TI）Bi $_2$ Se $_3$薄膜的电子能带结构.在Bi $_2$ Se $_3$ /EuS异质结构中，在拓扑状态的光谱中打开的间隙具有杂化特性，并且示出由Bi $_2$ Se $_3$膜厚度控制，而磁性对间隙的贡献小到可以忽略。我们还分析了Eu掺杂对Bi $_2$ Se $_3$薄膜的磁化强度的影响，并证明了Eu杂质在相邻的Se和Bi原子上诱导的磁矩比衬底诱导的磁矩大一个数量级。讨论了EuS/Bi $_2$ Se $_3$异质结的磁性和磁输运性质的最新测量结果。
Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and its magnetic coupling with ferromagnetic surface: first-principles study
Monolayer MnO$_2$ is one of the few predicted two-dimensional (2D) ferromagnets that has been experimentally synthesized and is commercially available. The Mermin-Wagner theorem states that magnetic order in a 2D material cannot persist unless magnetic anisotropy (MA) is present and perpendicular to the plane, which permits a finite critical temperature. Previous computational studies have predicted the magnetic ordering and Curie temperature of 2D MnO$_2$ with DFT+U (Density Funtional Theory + Hubbard U correction), with the results having a strong dependence on the Hubbard U parameter. Diffu…
To obtain accurate independent-particle descriptions for ferromagnetic two-dimensional van der Waals materials, we apply the quasiparticle self-consistent $GW$ (QSGW) method to VI$_3$, CrI$_3$, CrGeTe$_3$, and Fe$_3$GeTe$_2$. QSGW provides a description of the nonlocal exchange-correlation term in the one-particle Hamiltonian. The nonlocal term is important not only as the $U$ of density functional theory (DFT)+$U$ but also for differentiating occupied and unoccupied states in semiconductors. We show the limitations of DFT+$U$ in mimicking QSGW.
Magnetic, Optoelectronic, and Rietveld refined structural properties of Al3+ substituted nanocrystalline Ni-Cu spinel ferrites: An experimental and DFT based study
Hole sp3-character and delocalization in (Ga,Mn)As revised with pSIC and MLWF approaches - newly found spin-unpolarized gap states of s-type below 1% of Mn
Using density functional theory combined with a Hubbard model (DFT+U ), the electronic band structure of CrI3 multilayers, both free-standing and enclosed between graphene contacts, is calculated. We show that the DFT+U approach, together with the 'around mean field' correction scheme, is able to describe the vertical magnetotransport in line with the experimental measurements of magnetoresistance in multi-layered CrI3 enclosed between graphene contacts. Moreover, by interpolating between different double-counting correction schemes, namely the 'around mean field' correction and the fully loca…
With the intention to reveal the effect of the substitution, Ti-doped InSb alloy, we accomplished a first-principles prediction within the FPLAPW+lo method. We used GGA-PBEsol scheme attached with the improved TB-mBJ approach to predict structural, electronic, and magnetic properties of In$_{1-x}$Ti$_{x}$Sb with concentration $x = 0$, $0.125$, $0.25$, $0.50$, $0.75$, $0.875$, and $1$. Our lattice parameters are found in favorable agreement with the available theoretical and experimental data. The calculation shows that all structures are energetically stable. The substitutional doping transfor…
