29 research outputs found
Ab initio prediction of the high-pressure phase diagram of BaBiO3
No full textBaBiO3 is a well-known example of a 3D charge density wave (CDW) compound, in which the CDW behavior is induced by charge disproportionation at the Bi site. At ambient pressure, this compound is a charge-ordered insulator, but little is known about its high-pressure behavior. In this work, we study from first principles the high-pressure phase diagram of BaBiO3
using phonon mode analysis and evolutionary crystal structure prediction. We show that charge disproportionation is very robust in this compound and persists up to 100 GPa. This causes the system to remain insulating up to the highest pressure we studied
Ab initio study of ABiO3 (A=Ba, Sr, Ca) under high pressure
No full textUsing ab initio crystal structure prediction we study the high-pressure phase diagram of ABiO(3) bismuthates (A = Ba, Sr, Ca) in a pressure range up to 100 GPa. All compounds show a transition from the low-pressure perovskite structure to highly distorted, low-symmetry phases at high pressures (PD transition), and remain charge-disproportionated and insulating up to the highest pressure studied. The PD transition at high pressures in bismuthates can be understood as a combined effect of steric arguments and of the strong tendency of bismuth to charge-disproportionation. In fact, distorted structures permit to achieve a very efficient atomic packing, and at the same time, to have Bi-O bonds of different lengths. The shift of the PD transition to higher pressures with increasing cation size within the ABiO(3) series can be explained in terms of chemical pressure
Ab initio prediction of a two-dimensional variant of the iridate IrO2
No full textWe propose an insulating two-dimensional phase of IrO2, predicted by ab initio evolutionary algorithms. The predicted phase is a van der Waals crystal, in which Ir forms a triangular lattice, and is energetically competitive with the metastable spinel phase, observed experimentally. Electronic structure calculations show that the magnetic properties of this phase are highly nontrivial, with an almost perfect degeneracy of 120 Néel and
Y -stripe orders, and unusually soft magnetic moments. The resulting behavior, which we term easy plane anisotropy, is entirely different from what is realized in previously explored Kitaev honeycomb lattices. Our results thus suggest that IrO2 may be an ideal candidate to realize highly unusual magnetic properties
Pb10−xCux(PO4)6O: a Mott or charge transfer insulator in need of further doping for (super)conductivity
No full textWe briefly review the status quo of research on the putative superconductor Pb9Cu(PO4)6O also known as LK-99. Further, we provideab initioderived tight-binding parameters for a two- and five-band model, and solve these in dynamical-mean-field theory. The interaction-to-bandwidth ratio makes LK-99 a Mott or charge transfer insulator. Electron or hole doping (which is different from substituting Pb by Cu and thus differs from LK-99) is required to make it metallic and potentially superconducting.</p
Numerical data for "Origin of the anomalous Hall effect in Cr-doped RuO2"
No full text<p>This dataset contains the numerical data accompanying the "Origin of the anomalous Hall effect in Cr-doped RuO2" <a href="https://doi.org/10.1103/PhysRevB.111.064406" target="_blank" rel="noopener">paper</a>.<br>Computations were performed using <a href="https://www.vasp.at" target="_blank" rel="noopener">VASP</a> 6.3.0, and the postprocessing necessary to obtain the band structures was done using the <a href="https://vaspkit.com" target="_blank" rel="noopener">vaspkit</a> package.<br><br>The <code>Data</code> directory contains the necessary input files to reproduce the computations and the output files produced by the computations.<br>The <code>Plots</code> directory contains the data and gnuplot scripts used to plot figures presented in the paper:</p>
<ul>
<li>Fig. 1: energies and weighted average of local magnetic moments of various magnetic phases of Cr-doped RuO2 in the VCA approximation</li>
<li>Fig. 2: the absolute value of total magnetic moment with corresponding energy and local magnetic moment for a set of supercells of RuO2 with 20% Cr doping</li>
<li>Fig. 3: magnetic moment distribution for the two lowest-energy structures</li>
<li>Fig. 4: effective Curie-Weiss moments from Ref. [14] compared to a Cr-only model and anomalous Hall conductivity measured in Ref. [14] and its derivative with respect to the magnetic moment</li>
<li>Fig. 5: band-structure plots for the lowest-energy structure among the set of studied supercells</li>
</ul>
<p>To produce the figure one simply runs <code>plot.sh</code> script in the respective directory: the script will use <code>gnuplot</code> and <code>pdflatex</code> to produce the plots.<br>The data necessary to produce plots can be collected using the <code>get.sh</code> or <code>get_data.sh</code> scripts.<br>In the case of VASP computations, the total energy is reported in the <code>OUTCAR</code> file at the line containing the <code>free energy TOTEN =</code> token, the local magnetization in the block after the <code>magnetization</code> token, and the total magnetic moment in the <code>OSZICAR</code> file at the line containing the <code>mag=</code>token. The input parameters are specified in the <code>INCAR</code> file and the k-grid mesh in <code>KPOINTS</code> file. The pseudopotentials should be obtained from the VASP distribution and saved as a single file, named <code>POTCAR</code>.</p>
<p><br>The following POTCARs were used for VASP calculations:<br><code>md5sum name and location</code><br><code>b5c924befef4a180481bb6f65e4e516d potpaw_LDA.54/Ru_pv/POTCAR</code><br><code>6bfe8c9fc881319367b05c52d7f764ba potpaw_LDA.54/Cr_pv/POTCAR</code><br><code>dd29215744b63de40827d7952527f753 potpaw_LDA.54/POTCAR</code></p>
<h2>Licenses</h2>
<p>The data is licensed under CC-BY, the code (scripts) are licensed under MIT.</p>
A tool to check whether a symmetry-compensated collinear magnetic material is antiferro- or altermagnetic
No full textAltermagnets (AM) is a recently discovered class of collinear magnets that
share some properties (anomalous transport, etc) with ferromagnets, some (zero
net magnetization) with antiferromagnets, while also exhibiting unique
properties (spin-splitting of electronic bands and resulting spin-splitter
current). Since the moment compensation in AM is driven by symmetry, it must be
possible to identify them by analyzing the crystal structure directly, without
computing the electronic structure. Given the significant potential of AM for
spintronics, it is very useful to have a tool for such an analysis. This work
presents an open-access code implementing such a direct check.Comment: Submission to SciPos
Local symmetry groups for arbitrary wavevectors
No full textWe present an algorithm for the determination of the local symmetry group for arbitrary k-points in 3D Brillouin zones. First, we test our implementation against tabulated results available for standard high-symmetry points (given by universal fractional coordinates). Then, to showcase the general applicability of our methodology, we produce the irreducible representations for the ‘non-universal high-symmetry’ points, first reported by Setyawan and Curtarolo (2010 Comput. Mater. Sci. 49 299). The present method can be regarded as a first step for the determination of elementary band decompositions and symmetry-enforced constraints in crystalline topological materials.</p
AMCHECK: a tool to check whether a compensated collinear magnetic material is antiferro- or altermagnetic
No full textUp to now only a limited amount of altermagnetic materials were reported and a tool to predict if a given material is an altermagnet or not would be of great use for seeking new altermagnetic candidates. Utilizing the fact that the magnetic moment compensation in these systems is driven by symmetry, we developed a program/library that allows one to check if the given material is an altermagnet by using information about its crystal structure and magnetic pattern
A tool to check whether a symmetry-compensated collinear magnetic material is antiferro- or altermagnetic
No full textAltermagnets (AM) is a recently discovered class of collinear magnets that share some properties (anomalous transport, etc) with ferromagnets, some (zero net magnetization) with antiferromagnets, while also exhibiting unique properties (spin-splitting of electronic bands and resulting spin-splitter current). Since the moment compensation in AM is driven by symmetry, it must be possible to identify them by analyzing the crystal structure directly, without computing the electronic structure. Given the significant potential of AM for spintronics, it is very useful to have a tool for such an analysis. This work presents an open-access code implementing such a direct check
