In a recent Letter, S. Lounis et al. find that the ground state of finite antiferromagnetic nanowires deposited on ferromagnets depends on the parity of the number N of atoms and that a collinear-noncollinear transition exists for odd N. Authors use ab initio results and a Heisenberg model, which is studied numerically with an iterative scheme. In this Comment we argue that the Heisenberg model can much easier be investigated in terms of a two-dimensional map, which allows to find an analytic expression for the transition length, a central result of Lounis et al. (see their Fig.3).
Here we present a novel approach to control magnetic interactions in atomic-scale nanowires. Our ab initio calculations demonstrate the possibility to tune magnetic properties of Fe nanowires formed on vicinal Cu surfaces. Both intrawire and interwire magnetic exchange parameters are extracted from DFT calculations. This study suggests that the effective interwire magnetic exchange parameters exhibit Ruderman--Kittel--Kasuya--Yosida-like (RKKY) oscillations as a function of Fe interwire separation. The choice of vicinal Cu surface offers possibilities for controlling the magnetic coupling. Fur…
Interplay between structure and magnetism in $Mo_{12} S_9 I_9$ nanowires
我们用从头算密度泛函方法研究了Mo $_{12}$ S $_{9}$ I $_{9}$纳米线的平衡几何构型和电子结构.这些异常稳定的纳米线的骨架由刚性的官能化Mo八面体组成，通过柔性的双稳态硫桥连接。这种结构灵活性转化为几乎没有能源成本的情况下拉伸高达约20%的能力。纳米线从导体转变为窄隙磁性半导体，其结构异构体之一。
Mn doping of group-IV semiconductors (Si/Ge) is achieved by embedding a thin Mn-film as a δ-doped layer in group-IV matrix. The Mn-layer consists of a dense layer of monoatomic Mn-wires, which are oriented perpendicular to the Si(001)-(2x1) dimer rows, or Mn-clusters. The nanostructures are covered with an amorphous Si or Ge capping layer, which conserves the identity of the δ-doped layer. The analysis of the bonding environment with STM is combined with the element-specific detection of the magnetic signature with X-ray magnetic circular dichroism. The largest moment (2.5 μB/Mn) is measured f…
There has been renewed interest in the use of magnetic nanoparticles to convert high frequency electromagnetic energy into heat. During the last decade, numerous examples in the field of catalysis, lightweight thermoplastic composites for aeronautical and automotive engineering, and biomedical applications as well, have flourished. In a recent Letter "Ultrathin Interface Regime of Core-Shell Magnetic Nanoparticles for Effective Magnetism Tailoring", Moon et al. DOI: 10.1021/acs.nanolett.6b04016 claim to have observed a new interface spin canting phenomenon in core-shell ferrrites that pushes h…
Ab-initio calculations within Density Functional Theory combined with experimental Raman spectra on cluster-beam deposited pure carbon films provide a consistent picture of sp-carbon chains stabilized by sp^3 or sp^2 terminations, the latter being sensitive to torsional strain. This unexplored effect promises many exciting applications since it allows one to modify the conductive states near the Fermi level and to switch on and off the on-chain pi-electron magnetism.
In a recent article, A. Chen et al. claimed that they have switched (rotated by ~90 degrees) the magnetization of the soft layer of a magnetic tunnel junction (MTJ) in a non-volatile way with volatile strain by exploiting dipole interaction with the hard layer. I show that dipole interaction cannot cause this effect and the authors' explanation cannot be correct. An alternate explanation is offered.
In a recent Letter [PRL, 107, 047208 (2011)], Zorko et al. report on an "unexpected inhomogeneous magnetism" related to "a peculiar fragility" of the resonating-valence-bond (RVB) electronic state in the spin-1/2 quantum magnet CuNCN. Here, we show that: i) the spin model of the anisotropic triangular lattice (ATL), as proposed by Zorko et al., does not apply to CuNCN; ii) this model does not support the proclaimed RVB ground state in the relevant parameter range; iii) the magnetic state of CuNCN is not necessarily inhomogeneous.
The aim of this comment is to show that anisotropic effects and image fields should not be omitted as they are in the publication of A. Leonardi, S. Ryu, N. M. Pugno, and P. Scardi (LRPS) [J. Appl. Phys. 117, 164304 (2015)] on Pd <011> cylindrical nanowires containing an axial screw dislocation. Indeed, according to our previous study [Phys. Rev. B 88, 224101 (2013)], the axial displacement field along the nanowire exhibits both a radial and an azimuthal dependence with a twofold symmetry due the <011> orientation. As a consequence, the deviatoric strain term used by LRPS is not suitable to an…
Reply to the Comment by Tikhonov and Khrapai on "Long-range crossed Andreev reflection in a topological insulator nanowire proximitized by a superconductor"
In the paper "Andrew D.P. Smith, Peter T. Haugen, Boyd F. Edwards: Hysteretic transition between states of a filled hexagonal magnetic dipole cluster, Journal of Magnetism and Magnetic Materials 549 (2022): 168991" a hysteretic transition between two stable arrangements of a cluster of seven dipoles is presented. The relative strength of the center dipole in a hexagonal arrangement serves as the bifurcation parameter. The authors clearly demonstrate the existence of two instabilities accompanied by discontinuous jumps of the dipole arrangement, but leave the question about the nature of these …
Comment on "Neutron diffraction evidence of the 3-dimensional structure of Ba2MnTeO6 and misidentification of the triangular layers within the face-centred cubic lattice"
Indian Institute of Technology Madras（印度马德拉斯理工学院）；Jožef Stefan Institute（约热·斯蒂芬研究所）；University of Ljubljana（卢布尔雅那大学）；Paul Scherrer Institute（保罗谢尔研究所）
Comment on 'Observation of Shapiro Steps in the Charge Density Wave State Induced by Strain on a Piezoelectric Substrate'
Kotelnikov Institute of Radioengineering and Electronics of RAS（俄罗斯科学院科尔尼尼科夫无线电电子学研究所）；Moscow Institute of Physics and Technology (National Research University)（莫斯科物理技术学院（国立研究型大学））
The question of how ferroelectric polarization is coupled to magnetism in magnetoelectric multiferroics, in which both types of order are simultaneously present, is of considerable scientific and practical interest. A recent Letter \cite{fennie} presents an analysis of the important ``ABO$_3$'' class of perovskite multiferroics. This Letter argues that antiferromagnetic multiferroics with magnetic ions on the B site, such as the well-studied room-temperature multiferroic bismuth ferrite (A=Bi, B=Fe), cannot show linear magnetoelectric coupling of the form ${\bf P} \cdot ({\bf L} \times {\bf M}…
