Low-temperature electron properties of Heusler alloys Fe2VAl and Fe2CrAl: Effect of annealing

Подгорных, С. М.; Svyazhin, Artem; Shreder, E. I.; Марченков, В. В.; Dyakina, V. P.

doi:10.1134/s1063776107070102

Cited by 26 publications

(16 citation statements)

References 6 publications

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“…This upturn diminishes systematically with increasing Cr concentration in the series. As also demonstrated in Fe 2 VAl 17 and Ru 2 NbAl 18 Heuslers, such an upturn is mainly associated with the presence of magnetic clusters. Generally, the magnetic clusters present in any system rest at lowest energy at low temperature.…”

Section: Magnetic Properties Magnetization Of the Fe 2 Ti 1−x Crsupporting

confidence: 54%

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Half metallicity in Cr substituted Fe2TiSn

Chaudhuri

Salas

Srihari

et al. 2021

Sci Rep

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Band structure tailoring has been a great avenue to achieve the half-metallic electronic ground state in materials. Applying this approach to the full Heusler alloy Fe2TiSn, Cr is introduced systematically at Ti site that conforms to the chemical formula $${\text{Fe}}_{2} {\text{Ti}}_{{1 - x}} {\text{Cr}}_{x}$$ Fe 2 Ti 1 - x Cr x Sn. Compositions so obtained have been investigated for its electronic, magnetic, and electrical transport properties with an aim to observe the half-metallic ferromagnetic ground state, anticipated theoretically for Fe2CrSn. Our experimental study using synchrotron X-ray diffraction reveals that only compositions with $$x \le$$ x ≤ 0.25 yield phase pure L2$$_1$$ 1 cubic structures. The non-magnetic ground state of Fe2TiSn gets dramatically affected upon inclusion of Cr giving rise to a localized magnetic moment in the background of Ruderman–Kittel–Kasuya–Yosida (RKKY) correlations. The ferromagnetic interactions begin to dominate for x = 0.25 composition. Results of its resistivity and magnetoresistance (MR) measurement point towards a half-metallic ground state. The calculation of exchange coupling parameter, $$\hbox {J}_{{ij}}$$ J ij , and orbital projected density of states that indicate a change in hybridization between 3d and 5p orbital, support the observations made from the study of local crystal structure made using the extended X-ray absorption fine structure spectroscopy. Our findings here highlight an interesting prospect of finding half-metallicity via band structure tailoring for wide application in spintronics devices.

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Section: Magnetic Properties Magnetization Of the Fe 2 Ti 1−x Crsupporting

confidence: 54%

“…In such circumstance a modified equation, , is often used for description of specific heat 17 , 19 . The additional terms, 2 , accommodates the magnetic cluster formation with the quantity N being the number of clusters present in the system.…”

Section: Resultsmentioning

confidence: 99%

Half metallicity in Cr substituted Fe2TiSn

Chaudhuri

Salas

Srihari

et al. 2021

Sci Rep

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“…Such upturn in the low temperature heat capacity has also been found in Fe 2 VAl [55], Fe-V [56], TiFe alloys [57] where oscillation of small FM clusters have been argued to be responsible for this behavior. In those compounds, it was claimed that the system having ferromagnetic clusters in nonferromagnetic matrix normally rests in a position of minimum energy and the potential energy of the system gets enhanced when the direction of the magnetization vector of the clusters are altered due to the application of any force.…”

Section: Heat Capacitymentioning

confidence: 57%

“…So, due to thermal excitation, each cluster makes oscillation about a direction determined by its crystallographic anisotropy energy and absorbs k B T amount of thermal energy. This gives rise to an extra constant term C 0 ∼2k B N to the total specific heat [55,56], where N is the number of such oscillating magnetic clusters. However, to satisfy the third law of thermodynamics, which requires the heat capacity to be zero at T = 0 K, it is argued that this additional contribution, C 0 , gradually loses its strength below a certain temperature, called the Einstein temperature, crystal anisotropy energy [56].…”

Section: Heat Capacitymentioning

confidence: 99%

Ferromagnetically correlated clusters in semimetallic Ru2NbAl Heusler alloy and its thermoelectric properties

et al. 2018

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In this work, we report the structural, magnetic and electrical and thermal transport properties of the Heusler-type alloy Ru 2 NbAl. From the detailed analysis of magnetization data, we infer the presence of superparamagnetically interacting clusters with a Pauli paramagnetic background, while short-range ferromagnetic interaction is developed among the clusters below 5 K. The presence of this ferromagnetic interaction is confirmed through heat capacity measurements. The relatively small value of electronic contribution to specific heat, γ (∼2.7 mJ/mol-K 2 ), as well as the linear nature of temperature dependence of Seebeck coefficient indicate a semi-metallic ground state with a pseudo-gap that is also supported by our electronic structure calculations. The activated nature of resistivity is reflected in the observed negative temperature coefficient and has its origin in the charge carrier localization due to antisite defects, inferred from magnetic measurements as well as structural analysis. Although the absolute value of thermoelectric figure of merit is rather low (ZT = 5.2 × 10 −3 ) in Ru 2 NbAl, it is the largest among all the reported nondoped full Heusler alloys.

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“…Heusler alloys [1][2][3] can be attributed to unique functional materials, since they exhibit a wide variety of practically important properties, for example, a giant magnetocaloric effect, 2,4,5 shape memory effect, 2,6 unusual thermoelectric, thermal and semiconducting properties, [7][8][9][10] the properties of topological insulator and semimetal, 2,11 etc. A special place in this series is occupied by Heusler alloys, which are in the state of a half-metal ferromagnet (HMF) [12][13][14][15] and a spin gapless semiconductor (SGS).…”

Section: Introductionmentioning

confidence: 99%

Features of the electroresistivity, magnetic and galvanomagnetic characteristics in Co2MeSi Heusler alloys

Марченков

Perevozchikova

Семянникова

et al. 2021

Low Temperature Physics

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The electro-and magneto-transport as well as magnetic properties of Co 2 MeSi (Me = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys were studied. The electroresistivity was measured from 4.2 to 300 K, the galvanomagnetic properties (magnetoresistivity and Hall effect) were measured at T = 4.2 K in magnetic fields of up to 100 kOe, and the magnetization at T = 4.2 and 300 K in fields of up to 70 kOe. The normal and anomalous Hall coefficients, saturation magnetization, residual resistivity, current carrier concentration, coefficients at linear contributions into the electroresistivity and magnetoresistivity were obtained. It was shown that on the one hand, there is quite clear correlation between the electronic and magnetic characteristics of Heusler alloys studied, and the spin polarization coefficients of current carriers, taken from well know literature data, on the other hand. The obtained results can be used for creation of new materials for spintronics.

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Low-temperature electron properties of Heusler alloys Fe2VAl and Fe2CrAl: Effect of annealing

Cited by 26 publications

References 6 publications

Half metallicity in Cr substituted Fe2TiSn

Half metallicity in Cr substituted Fe2TiSn

Ferromagnetically correlated clusters in semimetallic Ru2NbAl Heusler alloy and its thermoelectric properties

Features of the electroresistivity, magnetic and galvanomagnetic characteristics in Co2MeSi Heusler alloys

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