Local moments in Mn-based Heusler alloys and their electronic structures

Plogmann, S.; Schlathölter, Thorsten; Braun, Jürgen; Neumann, M.; Yarmoshenko, Yu. M.; Yablonskikh, M. V.; Shreder, E. I.; Kurmaev, E.Z.; Wrona, Adriana; Ślebarski, A.

doi:10.1103/physrevb.60.6428

Cited by 136 publications

(101 citation statements)

References 39 publications

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“…31 Recently, Plogmann et al gave a detailed study on the degree of magnetic moment localization in various Mn-based full-Heusler alloys using x-ray photoelectron spectroscopy and x-ray emission spectroscopy ͑XES͒ techniques. 32 Depending on the atomic number of the Z element, the authors obtained from XES experiments an increasing localization of the Mn 3d states that is related to the larger interatomic distances for heavier sp ͑Z͒ elements. Furthermore, the authors compared the position of the Mn 3d peaks with first-principles calculations and obtained a very good agreement between the experiment and theory.…”

Section: B Magnetic Moments and Local Moment Behaviormentioning

confidence: 99%

“…Indeed, within the same family of alloys, one finds very different magnetic behaviors: itinerant and localized magnetism, ferrimagnetism, antiferromagnetism, helimagnetism, and other types of noncollinear ordering. [30][31][32][33][34][35][36] Despite a key role of the magnetism in the properties of Heusler alloys, experimental and theoretical studies of the exchange interactions in Heusler alloys are still rare. The first important information on the exchange coupling in these systems was provided by the inelastic neutron scattering experiments of Noda and Ishikawa 37 and Tajima et al 38 in the late 1970s.…”

Section: Introductionmentioning

confidence: 99%

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Role of conduction electrons in mediating exchange interactions in Mn-based Heusler alloys

2008

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Because of the large spatial separation of the Mn atoms in Heusler alloys ͑d Mn-Mn Ͼ 4 Å͒, the Mn 3d states belonging to different atoms do not overlap considerably. Therefore, an indirect exchange interaction between Mn atoms should play a crucial role in the ferromagnetism of the systems. To study the nature of the ferromagnetism of various Mn-based semi-and full-Heusler alloys, we perform a systematic first-principles calculation of the exchange interactions in these materials. The calculation of the exchange parameters is based on the frozen-magnon approach. The Curie temperature is estimated within the mean-field approximation. The calculations show that the magnetism of the Mn-based Heusler alloys depends strongly on the number of conduction sp electrons, their spin polarization, and the position of the unoccupied Mn 3d states with respect to the Fermi level. Various magnetic phases are obtained depending on the combination of these characteristics. The magnetic phase diagram is determined at zero temperature. The results of the calculations are in good agreement with available experimental data. Anderson's s-d model is used to perform a qualitative analysis of the obtained results. The conditions leading to a diverse magnetic behavior are identified. If the spin polarization of the conduction electrons at the Fermi energy is large and the unoccupied Mn 3d states lie well above the Fermi level, a Ruderman-Kittel-Kasuya-Yoshida-type ferromagnetic interaction is dominating. On the other hand, the contribution of the antiferromagnetic superexchange becomes important if unoccupied Mn 3d states lie close to the Fermi energy. The resulting magnetic behavior depends on the competition of these two exchange mechanisms. The calculation results are in good correlation with the conclusions made on the basis of the Anderson s-d model which provides useful framework for the analysis of the results of first-principles calculations and helps to formulate the conditions for high Curie temperature.

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Section: B Magnetic Moments and Local Moment Behaviormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of conduction electrons in mediating exchange interactions in Mn-based Heusler alloys

2008

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“…Theoretical studies of the microscopic origin of the magnetic anisotropy energy in some Heusler alloys indicated that the magnetic coupling has an orbital character and is mainly between atoms of the same species. Experimental findings have also shown that the magnetic properties of these ordered compounds depend significantly upon degree and type of chemical order [5][6][7][8]. The stoichiometric Heusler compound X 2 YZ crystallizes in the L2 1 structure (s.g. Fm3m), which consists of four interpenetrating fcc sublattices, each one occupied by one sort of atom.…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of the half-ferromagnetic Co2+x+yMn1-xAl1-y alloys

Paduani¹,

Migliavacca²,

Krause³

et al. 2007

Braz. J. Phys.

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Co 2+x+y Mn 1−x Al 1−y intermetallic compounds have been prepared by arc melting and studied with X-ray diffraction and magnetization measurements to ascertain the effect of deviations of composition from the stoichiometry on the ferromagnetism of this system. Hysteresis loops registered at room temperature show a soft ferromagnetic behavior in excess Co. In off-stoichiometric alloys the saturation magnetization is lower than in Co 2 MnAl, whereas the Curie temperature T C is higher in all the studied alloys. T C varies substantially with variations in composition and increases with the Mn content. In the source of this behavior a volume effect is inferred which is expected to lead to strengthened ferromagnetic exchanges.

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“…Due to noise in the experimental data, separation between the Mn 2p 1/2 sublevels is not so evident. Magnetic splitting of the Mn 2p 3/2 peak has been observed 15,16 in Co 2 MnSn and Pd 2 MnSn. This kind of splitting is considered to be the consequence of magnetic ordering in the alloy.…”

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confidence: 96%

Structural and magnetic phenomena in Ni53Mn25Al22 thin film prepared by rf magnetron sputtering

Srivastava

Chatterjee

et al. 2009

Applied Physics Letters

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Magnetic and structural properties of Ni-Mn-Al thin films are investigated. It is demonstrated that the annealed film shows L2 1 phase at room temperature. Magnetometry measurements reveal that the annealed film is ferromagnetic and a first order transition in magnetization versus temperature measurement confirms that the martensite to austenite transition occurs around room temperature. Transmission electron microscopy measurements confirm that this structural change occurs just below room temperature. The splitting of Mn 2p 3/2 level in x-ray photoelectron spectroscopy core level spectra of the annealed Ni-Mn-Al film, confirms that the origin of magnetism is definitely correlated with the local magnetic moment at the Mn atoms.

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Local moments in Mn-based Heusler alloys and their electronic structures

Cited by 136 publications

References 39 publications

Role of conduction electrons in mediating exchange interactions in Mn-based Heusler alloys

Role of conduction electrons in mediating exchange interactions in Mn-based Heusler alloys

Structural and magnetic properties of the half-ferromagnetic Co2+x+yMn1-xAl1-y alloys

Structural and magnetic phenomena in Ni53Mn25Al22 thin film prepared by rf magnetron sputtering

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