Hole -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

Milowska, Karolina Z.; Wierzbowska, Małgorzata

doi:10.1016/j.chemphys.2013.12.006

Cited by 9 publications

(12 citation statements)

References 44 publications

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“…Generally, the Mn-NN-pair along [110] crystallographic direction exhibits ferromagnetic alignment of the spins, whereas the Mn-NN-pair along [1 10] crystallographic direction prefers to be anti-ferromagnetically aligned. In addition, we have shown that the Mn 4p states have greater contribution to the hole states than 3d states, which is consistent with recently published theoretical results for bulk (Ga,Mn)As [45,46].…”

Section: Discussionsupporting

confidence: 92%

“…These empty states which are above the Fermi level and belong to the valence band can be identified with the hole states. As hole states, we consider unoccupied states with energies between Fermi energy (lying in the valence band) [44] and top of the valence band, as it was previously considered for a bulk system [45,46]. The hole states have mostly p character (see Fig.…”

Section: Electronic Structure and Spin Magnetic Momentsmentioning

confidence: 99%

“…Note that the same procedure was previously adopted in Refs. [45] and [46] for the bulk system. One can also consider integrated density of states N h,layer coming from the projected DOS for various slab layers.…”

Section: Electronic Structure and Spin Magnetic Momentsmentioning

confidence: 99%

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Energetic, electronic, and magnetic properties of Mn pairs on reconstructed (001) GaAs surfaces

2017

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We study energetic, magnetic, and electronic properties of diluted substitutional Mn-pairs on the reconstructed (001) GaAs surfaces. The studies are based on first-principles calculations in the framework of the density functional theory. We demonstrate that the stability of the systems strongly depends on the position, orientation, and the distance between the Mn-atoms constituting the pair. Independently of the considered surface reconstruction pattern, the Mn-pairs with Mn-atoms being the nearest neighbors (NN) on cationic sublattice turn out to be energetically more favorable than the pairs with the larger distance between the Mn-atoms. However, the preferential build-up orientation of the Mn-NN-pair depends on the surface reconstruction and is parallel either to [110] or [110] crystallographic direction. We reveal also the mechanisms of the magnetic ordering of Mn-NN-pairs. The Mn-NN-pairs along the [110] crystallographic direction exhibit always ferromagnetic alignment of Mn spins, whereas the spins in the Mn-NN-pairs along [110] direction are mostly anti-ferromagnetically aligned. In the electronic structure of the systems containing Mn-pairs with ferromagnetically aligned spins, we observe the valence band hole states in the neighborhood of Fermi energy. This indicates that the surface ferromagnetism in this prototype of dilute magnetic semiconductors can be explained in terms of the p-d Zener model.

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Section: Discussionsupporting

confidence: 92%

Section: Electronic Structure and Spin Magnetic Momentsmentioning

confidence: 99%

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Energetic, electronic, and magnetic properties of Mn pairs on reconstructed (001) GaAs surfaces

2017

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“…necessary. We used the k-point dependent procedure, being an extension of that used in the van der Waals functionals [17], and previously tested by us for GaAs doped with Mn [18].…”

Section: Computational Detailsmentioning

confidence: 99%

Cascade donor–acceptor organic ferroelectric layers, between graphene sheets, for solar cell applications

Wierzbowska

Wawrzyniak-Adamczewska

2016

RSC Adv.

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Organic ferroelectric layers sandwiched between the graphene sheets are presented as a model of the solar cell. The investigated systems display many advantageous properties: 1) the cascade energy-levels alignment, 2) simultaneous donor and acceptor character depending on the chargecarrier direction, 3) the charge-transfer excitonic type, 4) the induced polarization of the electrodes, leading to a substantial work-function change of the anode and cathode -around ±1.5 eV, respectively.PACS numbers:

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“…This fact implies that the Mn-induced modification of the (Ga,Mn)As VB observed in the LT-PR occurs for Mn content much lower than that, required for the development of the ferromagnetic coupling, as predicted by recent calculations. 65 On the other hand, and perhaps most importantly, the combined magnetic and LT-PR studies presented here univocally indicate that the PM ↔ FM transformation in carrier mediated DFS takes place without corresponding or underlying changes of the character of the valence (in the case of holes) band. The whole process is rooted in the nanoscale fluctuations of the local density of states (LDOS) and the SP-like "phase" can be regarded as the cornerstone of the DFS magnetism, serving as the pillar supporting the bridge spanning both PM and FM thermodynamic phases.…”

Section: Discussionmentioning

confidence: 51%

Band structure evolution and the origin of magnetism in (Ga,Mn)As: From paramagnetic through superparamagnetic to ferromagnetic phase

et al. 2018

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The high-spectral-resolution spectroscopic studies of the energy gap evolution, supplemented with electronic, magnetic and structural characterization, show that the modification of the GaAs valence band caused by Mn incorporation occurs already for a very low Mn content, much lower than that required to support ferromagnetic spin -spin coupling in (Ga,Mn)As. Only for n-type (Ga,Mn)As with the Mn content below about 0.3% the Mnrelated extended states are visible as a feature detached from the valence-band edge and partly occupied with electrons. The combined magnetic and low-temperature photoreflectance studies presented here indicate that the paramagnetic -ferromagnetic transformation in p-type (Ga,Mn)As takes place without imposing changes of the unitary character of the valence band with the Fermi level located therein. The whole process is rooted in the nanoscale fluctuations of the local (hole) density of states and the formation of a superparamagnetic-like state. The Fermi level in (Ga,Mn)As is coarsened by the carrier concentration of the itinerant valence band holes and further fine-tuned by the many-body interactions.

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Hole -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

Cited by 9 publications

References 44 publications

Energetic, electronic, and magnetic properties of Mn pairs on reconstructed (001) GaAs surfaces

Energetic, electronic, and magnetic properties of Mn pairs on reconstructed (001) GaAs surfaces

Cascade donor–acceptor organic ferroelectric layers, between graphene sheets, for solar cell applications

Band structure evolution and the origin of magnetism in (Ga,Mn)As: From paramagnetic through superparamagnetic to ferromagnetic phase

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