Physical properties of the tetragonal CuMnAs: A first-principles study

Máca, F.; Kudrnovský, J.; Drchal, V.; Carva, Karel; Baláž, Pavel; Turek, I.

doi:10.1103/physrevb.96.094406

Cited by 20 publications

(28 citation statements)

References 31 publications

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“…Together with the dynamically refined precession electron diffraction tomography, this agreement strongly suggests that copper occupies the basal positions of the structure (S 1 in Fig. 1) and this confirms the conclusions of the recent theoretical study of Máca et al [11].…”

supporting

confidence: 88%

“…Focusing on the tetragonal phase of CuMnAs, 10 we corroborate analysis of our spectral measurements by precession electron diffraction tomography (PEDT), which points to a phase recently claimed to have the lowest theoretically calculated total energy. 11 The studied thin films of CuMnAs were prepared by molecular beam epitaxy (MBE; we followed procedures described in Ref. 10).…”

mentioning

confidence: 99%

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Band structure of CuMnAs probed by optical and photoemission spectroscopy

et al. 2018

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Tetragonal phase of CuMnAs progressively appears as one of the key materials for antiferromagnetic spintronics due to efficient current-induced spin-orbit torques whose existence can be directly inferred from crystal symmetry. Theoretical understanding of spintronic phenomena in this material, however, relies on the detailed knowledge of electronic structure (band structure and corresponding wave functions) which has so far been tested only to a limited extent. We show that AC permittivity (obtained from ellipsometry) and UV photoelectron spectra agree with density functional calculations. Together with the x-ray diffraction and precession electron diffraction tomography, our analysis confirms recent theoretical claim [Phys.Rev.B 96, 094406 (2017)] that copper atoms occupy lattice positions in the basal plane of the tetragonal unit cell.Magnetic moments in antiferromagnets have been notoriously difficult to manipulate. With the exception of materials having low Néel temperature and small magnetic anisotropy, very strong magnetic fields must be applied. Such fields would be too strong to be of any practical use and, moreover, they can never be applied as locally as electric pulses. Recently, an alternative manipulation mechanism has been proposed 1 which relies on current-induced spin-orbit torques (SOTs) acting in the bulk of the antiferromagnetic material. They result from a build-up of staggered spin polarisation (i.e. the one which alternates sign on two magnetic sublattices) in response to an applied uniform electric current; such polarisation can be calculated in the framework of linear response to electric field. 2,3 A prediction of sizable SOT in CuMnAs has soon been experimentally confirmed 4 and prototype memories where the writing is done using SOT have been demonstrated. 5 Devices based on thin films of CuMnAs thus claim a prominent role within the fast developing field of antiferromagnetic spintronics. 6,7 Quantitative modelling of SOT (and many other material-specific quantities) relies on a detailed knowledge of the electronic structure. 8 While well-established ab initio methods have been used for this purpose, little effort has so far been dedicated to validating the band structure in terms of comparing calculated and measured spectral properties. 9 We fill this gap by exploring the complex AC permittivity in the optical range and photoemission spectroscopy in the UV range (UPS) and comparing them to density functional theory (DFT) calculations. We find a good agreement between the experimental data and the calculated properties provided the elec-tronic correlations are treated beyond DFT, using Hubbard model characterised by an on-site repulsion U on Mn 3d orbitals. Moreover, we demonstrate that the AC permittivity in the optical range can be used to discern different phases of CuMnAs. Focusing on the tetragonal phase of CuMnAs, 10 we corroborate analysis of our spectral measurements by precession electron diffraction tomography (PEDT), which points to a phase recently claimed to have the lowest ...

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confidence: 88%

mentioning

confidence: 99%

Band structure of CuMnAs probed by optical and photoemission spectroscopy

et al. 2018

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“…Similar to Ref. [25], we find that the formation energies of As and Mn vacancies in bulk are positive and negative, respectively. This implies that in the bulk the formation of a Mn vacancy is energetically favorable, whereas As vacancies are not likely to form.…”

Section: Defectsupporting

confidence: 89%

Emerging edge states on the surface of the epitaxial semimetal CuMnAs thin film

Nguyen

Pitike

Wadley

et al. 2020

Applied Physics Letters

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Epitaxial thin films of CuMnAs have recently attracted attention due to their potential to host relativistic antiferromagnetic spintronics and exotic topological physics. Here we report on the structural and electronic properties of a tetragonal CuMnAs thin film studied using scanning tunneling microscopy (STM) and density functional theory (DFT). STM reveals a blend of surface domains corresponding to two kinds of As-terminated surface reconstructions, and both domains show the expected semi-metallic behavior. An unexpected zigzag step edge surface reconstruction is observed with emerging electronic states below the Fermi energy. DFT calculations indicate that the step edge reconstruction can be attributed to an As deficiency that results in changes in the density of states of the remaining As atoms at the step edge. Our work provides a detailed understanding of the surface structure and step edges on the CuMnAs thin film, enabling in-depth studies of its topological properties and magnetism.

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“…The transport coefficients and exchange interactions applied in evaluation of resistivity and the Néel temperature are determined using the Green function formulation of the tight-binding linear muffin-tin orbital (TB-LMTO) method in which the effect of disorder (defects) is described by the coherent potential approximation (CPA) [12]. We have verified a good agreement between densities of states of ideal CuMnAs and alloy with Mn Cu -antisites obtained both by the supercell VASP and TB-LMTO-CPA calculations [8] used below to estimate the transport properties and exchange interactions.…”

Section: Formalismmentioning

confidence: 74%

“…The residual resistivity indicates the presence of defects whose origin and concentrations are known only very approximately [6]. Our previous study [8] identified the most probable defects but the evaluation of their formation energies represents a challenge for the theory. The same concerns also an estimate of the residual resistivity and the Néel temperature.…”

Section: Introductionmentioning

confidence: 99%

Tetragonal CuMnAs alloy: Role of defects

Máca

Kudrnovský

Baláž

et al. 2019

Journal of Magnetism and Magnetic Materials

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The antiferromagnetic (AFM) CuMnAs alloy with tetragonal structure is a promising material for the AFM spintronics. The resistivity measurements indicate the presence of defects about whose types and concentrations is more speculated as known. We confirmed vacancies on Mn or Cu sublattices and Mn Cu and Cu Mn antisites as most probable defects in CuMnAs by our new ab initio total energy calculations. We have estimated resistivities of possible defect types as well as resistivities of samples for which the X-ray structural analysis is available. In the latter case we have found that samples with Cu-and Mn-vacancies with low formation energies have also resistivities which agree well with the experiment. Finally, we have also calculated exchange interactions and estimated the Néel temperatures by using the Monte Carlo approach. A good agreement with experiment was obtained.

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Physical properties of the tetragonal CuMnAs: A first-principles study

Cited by 20 publications

References 31 publications

Band structure of CuMnAs probed by optical and photoemission spectroscopy

Band structure of CuMnAs probed by optical and photoemission spectroscopy

Emerging edge states on the surface of the epitaxial semimetal CuMnAs thin film

Tetragonal CuMnAs alloy: Role of defects

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