Physical properties of single crystalline CeNi<sub>4.2</sub>Mn<sub>0.8</sub>

Klimczak, M.; Talik, E.; Kusz, Joachim; Kowałczyk, A.; Toliński, T.

doi:10.1002/crat.200711030

Cited by 7 publications

(5 citation statements)

References 10 publications

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“…The confirmation of our prediction, however, requires further experimental studies, such as the X-ray photoemission spectroscopy ͑XPS͒. It is to be noted that the XPS valence-band spectra for CeMn 0.8 Ni 4.2 has been already reported by Klimczak et al 18 However, since this compound crystallizes in a hexagonal phase with supposedly different Mn-Ni and Mn-Ce distances, we think it is necessary to perform similar study on the cubic CeMnNi 4 so that one can have a correct comparison between the value of U Mn 3d obtained from our calculations with the corresponding experimental data.…”

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confidence: 77%

Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport inCeMnNi4

2010

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First-principles calculations are carried out to study the effect of electron correlations on relative structural stability, magnetism, and spin-dependent transport in CeMnNi 4 intermetallic compound. The correct description of Coulomb repulsion of Mn 3d electrons is shown to play a crucial role in reproducing the experimentally observed cubic phase of CeMnNi 4 as well as its relatively high degree of transport spin polarization ͑ϳ66%͒. These are the two fundamental properties of this compound which conventional density-functional theory approaches fail to predict correctly. The reason for this failure is attributed to an extreme overdelocalization of Mn 3d charges causing a strong d-d hybridization between Mn and Ni atoms in the orthorhombic phase. Such an artificial hybridization, in turn, lowers the relative total energy of the orthorhombic phase with respect to the cubic one. It also leads to an incorrect carrier concentration and mobility at the Fermi level and, consequently, yields much lower degree of transport spin polarization for this nearly half-metallic compound.Electron correlation plays a crucial role in understanding the electronic structure and magnetism in narrow-band systems. Density-functional theory ͑DFT͒ within its localdensity approximation ͑LDA͒ and generalized gradient approximation ͑GGA͒ turns out to be impressively successful in describing the ground-state properties of many materials. However, as an approximation, LDA/GGA faces serious difficulties for the strongly correlated systems, e.g. hightemperature oxide superconductors 1 and the middle-to-late transition-metal oxides. 2 Such a complication arises from the fact that the current implementations of DFT intrinsically tend to underestimate the Coulomb repulsion and, hence, fail to capture the correlation-driven charge localizations. Consequently, the conventional DFT calculations appear to underestimate or even close the band gap. They may even result in an incorrect description of the magnetic ground state. 3 Among the remedies to overcome this problem, the so-called LDA+ U approach 3 has already proven to be computationally one of the most efficient methods to study a large variety of strongly correlated systems, with considerable improvements over LDA and GGA. In this method, a strong intra-atomic interaction is introduced in a screened Hartree-Fock-type manner as on-site replacement of the LDA ͑GGA͒. Since the introduction of LDA+ U by Anisimov et al., 3 this formalism has been extensively utilized to investigate the electronic and magnetic properties of narrow-band systems. However, it has rarely been used to predict the correct structural phase stability of strongly correlated systems.It is already known that for some compounds, both LDA and GGA severely fail to predict the ground-state structure. An example for such systems is CeMnNi 4 . It is a unique intermetallic soft ferromagnet ͑FM͒ discovered recently, 4 which exhibits large magnetic moment ͑ϳ4.95 B / Mn͒, reasonably high Curie temperature ͑ϳ150 K͒, and a high degree of ...

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confidence: 77%

Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport inCeMnNi4

2010

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“…was observed [4,5]. The hexagonal structure has been also confirmed in our previous studies on the CeNi 4.2 Mn 0.8 crystal [8]. This structure is of the CaCu 5 -type and is well known for a wide range of the RNi 4 M compounds (R = Y or rare earth; M = Al, Cu, Si, Ga) [9][10][11][12], derived from RNi 5 .…”

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confidence: 71%

Neutron diffraction and magnetization measurements on CeNi_4.2Mn_0.8 and Y_0.7Ni_4.2Mn_0.8

Toliński

Kaczorowski

Kowałczyk

et al. 2008

Physica Status Solidi (b)

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The cubic CeNi4Mn compound has been claimed to show a large spin‐polarization, magnetic moment and a high Curie temperature. To verify these properties we have carried out the magnetometric and neutron diffraction experiments on the nominally polycrystalline CeNi4Mn and YNi4Mn compounds. The real stoichiometry was estimated based on X‐ray photoemission and neutron diffraction as CeNi4.2Mn0.8 and Y0.7Ni4.2Mn0.8. The magnetic properties of Y0.7Ni4.2Mn0.8 have been studied with neutron diffraction to investigate the role of the rare earth in CeNi4.2Mn0.8. We have found that the samples crystallize in the hexagonal CaCu5‐type of structure. The deviation from the cubic structure is ascribed to the presence of a small nonstoichiometry. These structural changes are accompanied by a drop of the magnetic parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…The remnant discrepancy with experiment may be due to ͑i͒ presence of compositional disorder ͑CeNi 4+x Mn 1−x ͒ in ac-tual sample, 22 which is out of scope in our calculations or ͑ii͒ due to noninclusion of the on-site Coulomb correlation for Mn. 23 The first effect is particularly important because of the different behaviors of the total DOS near Fermi level for the two spin channels.…”

Section: B Theoretical Calculationsmentioning

confidence: 72%

Understanding the role of structural disorder on spin polarization inCeMnNi4using XAFS

et al. 2010

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The role of disorder on ferromagnetism has generally been detrimental. We show how Mn-Ni antisite disorder enhances polarization in CeMnNi 4. The disorder is determined to be 6% by x-ray absorption fine structure. The electronic structure of pure CeMnNi 4 is pseudo-half-metallic. Site exchange alters the near neighbor bond parameters and modifies the density of states favorably, increasing the polarization ͑obtained by first-principles calculations͒ from 13 to 47% ͑experimental ϳ66%͒.

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Physical properties of single crystalline CeNi_4.2Mn_0.8

Cited by 7 publications

References 10 publications

Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport inCeMnNi4

Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport inCeMnNi4

Neutron diffraction and magnetization measurements on CeNi_4.2Mn_0.8 and Y_0.7Ni_4.2Mn_0.8

Understanding the role of structural disorder on spin polarization inCeMnNi4using XAFS

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Physical properties of single crystalline CeNi4.2Mn0.8

Cited by 7 publications

References 10 publications

Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport inCeMnNi4

Effect of electron correlations on structural phase stability, magnetism, and spin-dependent transport inCeMnNi4

Neutron diffraction and magnetization measurements on CeNi4.2Mn0.8 and Y0.7Ni4.2Mn0.8

Understanding the role of structural disorder on spin polarization inCeMnNi4using XAFS

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Physical properties of single crystalline CeNi_4.2Mn_0.8

Neutron diffraction and magnetization measurements on CeNi_4.2Mn_0.8 and Y_0.7Ni_4.2Mn_0.8