Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · cond-mat/0212093

Spin interactions of interstitial Mn ions in ferromagnetic GaMnAs

J. Blinowski·P. Kacman
View original source ↗Read source document ↗Export metadata ↓

Abstract

The recently reported Rutherford backscattering and particle-induced X-ray emission experiments have revealed that in low-temperature MBE grown GaMnAs a significant part of the incorporated Mn atoms occupies tetrahedral interstitial sites in the lattice. Here we study the magnetic properties of these interstitial ions. We show that they do not participate in the hole-induced ferromagnetism. Moreover, Mn interstitial double donors may form pairs with the nearest substitutional Mn acceptors - our calculations evidence that the spins in such pairs are antiferromagnetically coupled by the superexchange. We also show that for the Mn ion in the other, hexagonal, interstitial position (which seems to be the case in the GaMnBeAs samples) the p-d interactions with the holes, responsible for the ferromagnetism, are very much suppressed.

Explore related subjects

cond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J. Blinowski, P. Kacman. 2002-12-04. Spin interactions of interstitial Mn ions in ferromagnetic GaMnAs. https://doi.org/10.1103/physrevb.67.121204

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Coexistence of Donor and Acceptor Hydrogen States in n-Type InN

Hydrogen often exhibits amphoteric behavior in semiconductors, but its role is in n-type InN remains unresolved. Wurtzite InN is a narrow-gap semiconductor with high electron mobility and is therefore attractive for high-speed electronics and optoelectronic applications. Here we use hard x-ray photoemission spectroscopy (HAXPES) to probe hydrogen-related electronic structure in as-grown and post-annealed InN thin films prepared at different grown temperatures. Post annealing, which reduces the concentration of hydrogen impurities in the films, shifts the core-level spectra toward lower binding energy, consistent with a chemical-potential shift associated with the passivation of electron carriers. In the valence-band spectra, an acceptor-like in-gap feature near the valence-band maximum is suppressed after annealing. Together with the established donor-like behavior of hydrogen in InN, these results suggest that acceptor H- states coexist with donor H+ states in InN. The coexistence of these opposite hydrogen charge states provides a microscopic picture of hydrogen-driven compensation in InN and highlights the amphoteric nature of hydrogen even in a highly n-type semiconductor.

cond-mat.mtrl-sci↗
arXiv2026

Updated Tkatchenko Scheffler method and assessment of dispersion methods for alkali-containing systems

The Tkatchenko-Scheffler (TS) pairwise method to calculate dispersion interactions is a widely used approach to incorporate missing long-range van der Waals contributions in semilocal and hybrid density functional calculations. Despite subsequent many-body extensions, this formulation remains widely used. In 2018, Fedorov et al. reported updated van der Waals radii to the seminal work published in 2009. The present work examines the accuracy of the TS method with updated van der Waals radii (TS_2018), coupled with the semilocal Perdew-Burke-Ernzerhof density functional, for structural predictions of semiconducting and insulating materials. Special attention is paid to materials containing alkali elements, for which the TS_2009 method exhibits a large overbinding, associated with potentially large errors in predicted atomic structures. We also consider a narrower reformulation (TS_alkali) where only the the alkali atoms are corrected, so the method remains otherwise compatible with TS_2009. We compare these methods with a broader set of dispersion corrections--the DFT-D3 method, the exchange-hole dipole moment method, and the beyond-pairwise, nonlocal many-body dispersion method--for ionic and alkali-containing systems more generally. We examine equilibrium geometry predictions for 45 inorganic solid compounds as well as three Cs-containing halide perovskites, CsPb$X_3$ ($X$ = Cl, Br, I). Our results show that the updated van der Waals radii in the TS_2018 and TS_alkali methods resolve the overbinding that is present with TS_2009 in alkali-containing systems, bringing predictions into closer agreement with other dispersion methods. For the halide perovskites, method-dependent differences in predicted cell volumes and shapes persist, and no approach performs with perfect accuracy on all metrics for all three materials.

cond-mat.mtrl-sci↗
arXiv2026

Hierarchical Fourier Phase Projection for Local Electronic Observables

In this letter, we develop hierarchical Fourier phase projection (HPP) for the calculation of local electronic observables. The method couples the spatial decay of the density matrix with a hierarchy of Fourier probes, improving accuracy through refinement, and making use of all previously evaluated responses. The variation in the calculated observables during the refinement process carries information on the residual error. We use a locality-based model to estimate the error from these changes with no extra probing calculations. In particular, we demonstrate the method for electron densities and nonlocal pseudopotential forces for fixed Kohn-Sham Hamiltonians of semiconductors, metals and thermally perturbed silica. The convergence is significantly accelerated by the spatial decay of the density matrix, especially if the density matrix is short-ranged. The number of probes necessary to achieve a specific local accuracy is only weakly dependent on the system size within the range of consideration. HPP provides a route toward linear-scaling electronic-structure calculations in which the computational effort for local observables can be matched to the required accuracy, offering an error-aware strategy for large-scale first-principles simulations.

cond-mat.mtrl-sci↗