Papers by Keyword: Heusler Alloy

Abstract: The Heusler alloy system is a rich source of functional materials. We studied the ternary alloy Ti₂NiSb by first-principles calculations to explore for new functional alloy. We performed geometry optimization for the alloy with Hg₂CuTi-type structure and the obtained equilibrium lattice parameter is a₀=6.21 Å. The magnetic moments of atom Ni is 0.22μ_B in one cell. The alloy is a ferromagnet. The little magnetic moment of atom Ni comes from the characteristic spatial occupation of the atoms in the space structure of the alloy.

Abstract: We studied a new Heusler alloy V₂CoSi with Hg₂CuTi-type structure by first-principles calculations. The electric structure and magnetic properties have been investigated. The alloy has a total magnetic moment of 1.00μ_B per unit cell on first-principles calculations which is in agreement with the SlaterPauling (SP) rule. The magnetic moment of atom Co is 0.38μ_B and the magnetic moments of V(1) atom and V(2) atom are 0.80μ_B and-0.24μ_B respectively, so the alloy is a ferrimagnetism.

Abstract: The phase transformation and magnetic properties of Heusler-type Ni₅₀Mn_50-xIn_x (x=10~16) ferromagnetic shape-memory alloys have been systemically investigated by differential scanning calorimetry and vibrating sample magnetometry. It is found that the phase transition temperatures show a linear relationship with the In concentration and the curie temperatures of austenite phases are not sensitive to the alloy composition. The existence of large magnetization change during the magneto-structural transition is the origin of magnetic-field-induced transformation effect.

Abstract: A new Heusler alloy V₂NiGa with Hg₂CuTi-type structure was investigated by first-principles calculations. The band structures and magnetic properties have been studied. The alloy has a total magnetic moment of 1.05μ_B per unit cell on first-principles calculations which is in agreement with the SlaterPauling (SP) rule. The magnetic moments of V(1) atom and V(2) atom are 1.28μ_B and-0.44μ_B respectively, so the alloy is a ferrimagnetism.

Abstract: The band structures and magnetic properties of Heusler alloy Cr₂ZrGe with Cu₂MnAl -type have been investigated by first-principles calculations. The alloy is predicted to be close to half-metal ferromagnet. The alloy has a total magnetic moment of 3.98μ_B per unit cell on first-principles calculations which is in agreement with the SlaterPauling (SP) rule. The magnetic moments of Cr(A) atom and Cr(C) atom which are both much larger than that of atom Zr(C) are same. This similarity comes from similar atom coordination surroundings of Cr(A) and Cr(C) atoms in crystal structure.

Abstract: The electronic structures and magnetic properties of full-Heusler alloy Ti₂CoSi with Hg₂CuTi-type have been investigated by first-principles calculations. The compound is predicted to be a potential half-metal ferromagnet. The calculations show that there is an energy gap in the minority spin of the band structures whereas the other spin is strongly metallic, which results in a complete spin polarization of the conduction electrons at the Fermi level. The compound has a total magnetic moment of-3.0μ_B per unit cell on first-principles calculations which is in excellent agreement with the SlaterPauling (SP) rule. The magnetic moments of Ti(A) atom and Ti(B) atom which are both larger than that of atom Co(C) are different. This difference comes from different atom coordination surroundings of Ti(A) and Ti(B) atoms in crystal structure.

Abstract: Ti-based Heusler compounds are rare reported widely up to now. In this paper, ternary full-Heusler compound Ti₂NiIn is systematically studied by first-principles calculations. The calculations show the compound has a complete spin polarization around the Fermi level in the total density of state. The majority spin shows strongly metallic character, while the minority spin has an insulating behavior in its band structure. The compound has a precisely total magnetic moment of-3.0μ_B per formula by first-principles calculations. This result complies well with the SlaterPauling (SP) rule. All the results show that Ti₂NiIn with Hg₂CuTi-type structure is a new half-meltal ferromagnet by first-principles calculations.

Abstract: The tuning exchange bias H_E at martensitic state of Ni₅₀Mn₃₆Sn₁₄ alloy has been investigated by means of hysteresis loop measurement. It was found that the whole loop can be tuned by H_FC from a double-shifted to a single-shifted hysteresis loop, leading to an appearance of maximum H_E at H_FC = 0.5 kOe. This behavior could be ascribed to the competition between two types of AFM clusters and H_FC, which exhibits predominantly at low H_FC range, while the competition between FM clusters and H_FC, which becomes predominant at high H_FC range.

Abstract: Effect of Co or Cu slightly introduced in Ni₅₀Mn₃₅In₁₅ on martensitic transformation and magnetocaloric effect was investigated. The small doping of Co can modify exchange interaction between Mn atoms, resulting in the ferromagnetic ordering of the parent phase and a large magnetization difference across the martensitic transformation. For Cu-doped sample, a large was obtained, and gives rise to a large magnetic entropy change of 58.4 J/kg K for 5 T near room temperature accompanying with smaller hysteresis losses. The study on the doping system may have significant impact on realization of room-temperature magnetic refrigeration.

Abstract: Two representatives of Ni(Co)-Mn-Al metamagnetic shape memory alloy system, Ni45Co5Mn31Al19 and Ni35Co15Mn35Al15, have been studied with respect to their magnetocaloric properties. Experimental study of the magnetocaloric effect by a direct measurement of the adiabatic temperature change ΔTad revealed that in both the samples ΔTad depends on the measurement protocol as well as on the magnetic prehistory of the samples. For the applied magnetic field µ0H = 1.93 T, the largest adiabatic temperature change, |ΔTad| ~ 0.7 K, has been observed in the Ni35Co15Mn35Al15 sample at T = 464 K.